From: Commander Assault Force "U".
Such small difficulties as were encountered in Communications may be attributed to two major causes:
Inexperience of personnel, both officer and enlisted, most of whom had never participate in an Amphibious Operation before and
The short length of time allowed to correct and read the voluminous orders and numerous publications involved. The use of three separate systems of generating call signs, plus the use of locally assigned pronouncable R/T call signs, created an unduly complicated procedure. Promulgation of these local R/T calls was difficult and often incomplete.
Circuits--During the initial phase of the Assault, the Force Flagship guarded 51 circuits. This includes Array Ground Force, Army Air Force, and USN Circuits. As Army elements moved ashore, the number of circuits was considerably reduced. However, 24 Navy circuits were guarded from D minus 1 to D plus 9 day, when the Build-up phase was entered and the numbers of circuits reduced to 15. In spite of the high number of circuits involved, little mutual interference was encountered.
The TBS on 72.5 Mcs was used heavily, without scrambler. The KGA scrambler unit failed to function properly, causing a tremendous drop in signal strength and producing poor speech difficult to understand. The use of the TBS "plain" resulted in some loss of security, which was more than made up by urgency of items of nature that could be disguised.
Circuits could have been reduced in number for the Assault phase. Of the three Broadcast circuits from U.K. only Area CN carried a heavy volume of traffic. SN and WN Broadcasts were relatively light, and often required the use of "dummy" traffic to keep up the load. The elimination of one of these circuits would have helped. The use of automatic transmitters on all Broadcast channels would have aided copying, relieving the receiving operators of the necessity of adjusting themselves to the individual peculiarities of the transmitting operators.
As in previous operations, the Common Bombardment calling Wave was not utilized by WTF Forces, the TBS and common FM channel being used instead. This circuit could be eliminated in future operations insofar as U.S. Forces are concerned. No transmissions were heard on this circuit aboard the Force "U" Flagship.
FM Boat Control circuits operated very well considering the high
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number of stations on each circuit. Some enemy jamming was encountered, but it was not sufficient to prevent use of the circuit. Procedure was fair, and security low. The circuits were utilized long after they could have been secured. This was partly due to a tendency to use this channel to clear all traffic to and from the beach, and also due to delay in establishing the Ship-Shore CW Channel because of loss of equipment by "drowning".
There is an overwhelming tendency to use voice channels as a telephone, and disregard the low security of any R/T circuit. An R/T circuit has much lower security than a CW Channel, since an operator must copy CW while it may be assumed that anyone can understand spoken words.
Authentication worked quite well, even though there were three authenticators in use. Little bogus traffic was encountered, and after D plus 2, operators were able to recognize other stations by their operating procedure and/or voice characteristics. Authentication was demanded on all important messages.
Publications--It is felt that the introduction of standard British publications caused considerable confusion to USN Forces, since they were uncorrected and corrections were not supplied. This was particularly true on the delivery groups used on the broadcasts. Further, such corrections to publications as were supplied were so numerous, and the time available for correction so short, that many of the ships and craft were unable to complete before sailing. No Reserve on Board was prescribed, and certain publications which have subsequent issues were not available at a central location. In particular, the Combined Assault Code in current use was compromised. No subsequent edition has been made available, with the result that LOXO is severely overloaded and is increasingly open to compromise. These are low grade codes for use with landing craft and represent the only means of passing confidential and secret information to these craft.
The two letter and voice calls in S.P. 2573 were very useful, but should have been allocated to the Task Force Commanders rather than the Headquarters Ships they were in. If the Task Force Commanders had changed Headquarters Ships, there would have been no call sign for them.
S.P. 2573 (E.T.O. Call Sign Book) should have been brought into force before the first convoy sailed. When the postponement was ordered, some slow convoys had sailed. There was considerable uneasiness over the delivery of the postponement message, since a general call (All ships reading port wave) had to be used. Fortunately it worked.
RCM--The equipment on the Force "U" Flagship functioned excellently. Forty-two indications were received and jammed. There is no indication that any ship of Force "U" was struck by a radio controlled bomb.
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Radar--All equipment functioned very well. Due to Army reports that the enemy was using 180 Mcs. radar to "home" on for bombing purposes, on D plus 9 the SC radar was secured daily from 2200B to 0530B.
Traffic--The volume of traffic was heavy, partially due to ignorance of arriving ships, craft, convoys as to what they should do after arriving in the Assault Area. Numerous ships destined for OMAHA Beach appeared at UTAH Beach and required additional routing instructions. From D to D+5 day traffic averaged 500 messages incoming and outgoing, radio and visual. From D plus 6 to D plus 9, average was 400; from D plus 9 on the average was 300 daily. Due to the hard work of all hands, only three messages were seriously delayed. When these were discovered, corrective action was immediately instituted. A standard system of distribution was used, and the Army Ground and Air Forces were provided with a copy of all Naval traffic during their stay aboard. They reciprocated by providing the Navy with a copy of their traffic, which greatly helped coordination.
Visual--Visual Communications worked well considering the inexperience of personnel involved. The installation of a British Daylight Signalling Lantern Pattern Number 443 on Force "U" Flagship proved extremely useful in transmitting "All Ships Present" signals. At first some difficulty was experienced in getting all ships to read these signals, but this was soon overcome. Few flag hoists were made, as flashing light proved more satisfactory. Semaphore was used whenever practicable.
Circuits--That every attempt be made to reduce the number of radio circuits. The present tendency is to increase these channels. If automatic transmitters were used on shore to ship broadcasts, the useful circuit time could be greatly increased, without increasing the speed of transmissions. If duplicate frequencies, instead of duplicate channels were prescribed, fewer circuits, using the best frequency, could be maintained.
Authentication--Keep as simple as possible coincident with security. Avoid cumbersome tables such as LOXO Cards. No authenticator table should be larger than 8 x 10 inches, preferably about 4×6 inches for easy handling. Sufficient copies of authenticators should be provided to permit each operator on a circuit to have a copy.
Equipment--The Bayfield has many objectionable features, due to lack of space and equipment, to serve as an AOC, which it had to do in this operation. It is not desirable to use a troop carrying transport as a Communications Headquarters Ship. Even when designed as a relief AOC (as the Bayfield was) there is too much additional equipment to be added.
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Publications--Once again, too many and too complicated. This applies particularly to call signs. If S.P. 2573 had been used alone, much less confusion would have resulted. Further, provision must be made for Reserve on Board editions for changes in effective publications. All publications issued before an operation should be corrected up to date of issue. This is extremely important as landing craft and small ships do not have the personnel or facilities for correcting. Where publications of one service are issued up to date of issue, plus instructions on where to look for future corrections (D.A.'s at British Bases) (I.O.'s at U.S. Bases) and Admiralty General Messages should be included. For USN publications issued to British ships, similar pertinent information must be supplied.
Security--The need for communication security must be ever stressed. The choice of speed by voice transmission versus loss of security must ever be considered. In general it is believed speed of operation during the Assault phase is predominant.
From: Commander Assault Force "O", (Commander Eleventh Amphibious Force).
Planning. It became apparent early in the planning that the availability of radio communication channels would probably be one of the limiting factors governing the scope of the operation, and that each increase in the forces taking part would necessarily result in a lowering of the overall efficiency of communication.
From the radio point of view, the operation was unique in that its theatre was in an area of extremely high density of radio and radar transmission. The progress of the war in Europe had resulted in a large number of radio transmitters, fixed and mobile, in a small area. Many powerful broadcasting stations were operating in all bands of the frequency spectrum, and their heavily modulated emissions, together with a multitude of jammers of all descriptions left practically no points on a radio dial on which signals were not heard.
The operation was also unique in that an unusually long time was available for planning. However, this was not an entirely advantageous situation, as operational planning introduced many changes which kept confusing the communication picture.
The actual planning suffered somewhat from a lack of a coordinated "plan for planning". The first publication appearing was "Signal Instructions for Naval Assault Forces". This arrived early in the fall of 1943, and was followed by a series of "Signal Planning Memoranda" which were intended to amplify the earlier instructions but
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which also replaced them to an extent which was not entirely clear. Then later came PONCOs which were in turn replaced by ONCOs. In addition there were voluminous "appreciations", "memoranda", etc.
The ONCOs issued by the Allied Naval Commander Expeditionary Force arrived in good time and. were used in preparation for the Assault Force Communication Plan. The Task Force Commander's Plan did not arrive in time to be used, but close personal cooperation in planning eliminated any confusion because of this.
As D day approached, a serious situation arose with respect to communications planning. A flood of apparently non-essential changes to ONCOs began pouring in, which clogged communication channels. For example, Coast Guard Cutters (sea rescue boats) were directed not to use the calls shown in the Call Book but were to use "C.G.C. followed by numbers". In Force "O" it became necessary to screen carefully the mass of changes and promulgate only those essential to the operation.
It is recommended that in future operations of this magnitude, a basic i>lan be outlined and issued in the early stages and that this single publication be the foundation upon which the final plan is ultimately built.
The requirements of security just prior to the operation imposed considerable restriction on the use of radio. Full reliance had to be placed on the teletype network which was heavily overloaded. It was impossible to handle communications through the normal chain of command, as the assault group commanders had a miscellaneous and often widely scattered group of ships and craft under their command. The organization, which proved to be excellent as far as the assault was concerned, was troublesome for communication purposes before and after the assault phase. The usual administrative organization disappeared as the assault organization became effective, and as a result many last minute changes never reached all elements of the force.
The volume of plans affecting communications reached enormous proportions before D day, because of the wide distribution of higher echelons of the various Army and Air Force organizations and excessive duplication of plans as the lower levels were reached. The duplication was necessary in order that the smaller craft and units would get information they needed which was contained in plans not distributed to them.
Frequency Assignments, ^he assignment of frequencies was an extremely difficult task but was exceptionally well handled by the Staff of the Allied Naval Commander Expeditionary Force. Blocks of frequencies were assigned the Navy, Army and Air Forces by the Supreme Commander, and allocations to the various units made from these blocks. The very large and varied elements which composed each assault force
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contained many types of radio equipment, some British and some American. Frequencies had to be selected which were within the range of these sets, and so far as is known, no ship was assigned a frequency which it could not guard. It was impossible to assign frequencies which made the best utilization of all equipment, because there were simply not enough "good* frequencies to go around, but the overall result was satisfactory for all purposes. The frequencies for the FM radiotelephone sets were assigned by blocks with a number of adjacent frequencies assigned a single force. This resulted in unnecessary interference in the flagships. It is recommended that in future assignments adjacent frequencies be scattered among separated forces, and not assigned by blocks. The noise level on board the flagship was high because of the large number of frequencies in use, but only one case of serious interference was noted. The V Corps command net on 35.5 mcs. and the Tactical Reconnaissance frequency of 141.84 mcs. both used a crystal on 7880 kcs. Communication was possible on only one of these nets at a time.
Extensive jamming was expected, as the enemy had the advantage of a long established and complete wire network whereas we were forced to use radio. Surprisingly, however, no jamming was experienced on any of the frequencies used by this force. It may be possible that the enemy endeavored to gain useful information by listening to our transmissions rather than cause us the inconvenience of jamming.
The exceptionally large number of circuits manned was probably greater than were ever before established on board a single ship, and exceed by far the number of channels handled by many of our large shore communication centers. In addition, the visual facilities of the ship were utilized fully, resulting in a tremendous volume of traffic, especially on D day and for several days thereafter. After the Army was well established ashore and had moved inland, the traffic decreased considerably.
An innovation in internal organization which proved very satisfactory was the use of three Navy "C.W.O.'s" on watch at a time. One officer occupied the usual desk alongside the Army C.W.O. in the communication office, one was stationed beside the Navy Operations Officer in the Joint Operations Room and one was stationed in Flag Plot. Each of these officers was fully qualified to handle any communication problem which came up, and their actions were coordinated through a direct telephone circuit reserved for their use. This scheme merits trial on all large amphibious flagships.
Internal distribution of messages created quite a problem. For three months prior to D day intensive drills were conducted by the organization set up to handle the messages, and various changes and improvements made as a result of these drills. It was found necessary to make some changes in the teletype arrangements, as the teletypes
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were used for distribution of copies as well go projecting the messages on the visual screens. The system finally used was entirely successful and no failures of internal distribution were reported.
Jamming equipment designed to protect the ship from radio guided missiles was installed and tested prior to D day. The efficient employment of this installation required practically instantaneous communication between the visual observer on the ship's stack and the operating crew of the jamming equipment. It also required prompt information to the officer controlling the Joint Force Broadcast to enable him to get out a warning to other ships and craft, The arrangement worked satisfactorily, but the efficiency of the jamming installation was reduced by inexperienced personnel in other ships turning on their jammers unnecessarily, thus producing false indications on the screen of search receivers. One vessel in particular on several very dark nights and with 10 flares being used turned on their jammer and repeated over the TBS the signal calling for the Jamming of suspected control signals. The element of surprise necessary for the successful use of the jammers was thereby jeopardized. As it developed, no radio guided missiles were observed in our area and no practical test of the equipment was possible. The Radar Countermeasures Team is of the firm opinion that three radio guided missiles were launched near the ship but these were not confirmed by visual observations.
The TBS channel, which has become a primary means of action communication in the U.S. Navy, was not available for this purpose in the early part of the operation. An elaborate scheme of ship-shore communications was planned, consisting of several high powered radiotelephone stations along the south coast of ENGLAND established on high ground and using rotatable directional antennas. These stations were connected to the shore combined headquarters and to the regular British telephone system. They were intended to work with the shipborne TBS equipment in the amphibious force flagships, which had been fitted with British telephone speech privacy equipment. As the security of these "scramblers" is very low, it was not considered desirable to test them out prior to the operation. After radio silence was broken on D day, attempts were made to use the system as designed, but all efforts were futile. Finally the TBS equipment was used for its normal purpose in the Western Task Force. Later the shore stations were heard and communication established. Service between the ships and shore was excellent up to a distance of about 100 miles. This proved that the TBS is by no means a "limited range" method of communication, as the transmission could be heard easily by the shore stations. The ship-shore and cross channel radiotelephone channels were an expensive innovation and so little used by American commands that their use in future operations is not recommended.
Two large scale charts were posted in the code room. One chart listed the crypto channels held by all British and U.S. units involved
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in the operation. The other chart listed the publications used for each channel. These charts were very useful and resulted in the complete elimination of incoming service messages pertaining to crypto channel errors. A large radio frequency chart was also posted in Radio I.
The cooperation of the operations officers and other users of the communication system was all that could be desired. Dispatches were brief and carefully drafted, information addressees kept to a minimum and references to other dispatches avoided wherever possible. During high speed amphibious operations it is impossible to look up previous references without delaying traffic to a point where operations are seriously impeded.
The communication equipment of the flagship performed in a highly satisfactory manner. The large number of transmitters in simultaneous operation naturally resulted in a high noise level and severe key clicks, but careful preparation of equipment paid big dividends. All keying relays were cleaned and adjusted, and all antenna insulators cleaned and polished. The latter step is particularly important and noticeably reduced the noise. This ship has on board a large number of Model RAO receivers which are not suitable for use in amphibious flagships. It is recommended that they be replaced by Model RBG or similar receivers during the next overhaul period. The Model TBK-12 transmitter was the source of most of the unwanted emissions and both that transmitter and its antenna will be examined to determine if corrective measures Can be taken.
Because of her superior communications as compared to the Augusta, the Ancon performed several duties which would normally have been done by the Task Force Flagship. The Ancon carried the headquarters of the Commanding General Fifth Corps, Commanding General, First Division, and the Commanding General Engineer Special Brigade Group. There was no adequate alternate flagship available in case the Ancon became a casualty. The U.S.S. Baldwin was designated as the relief flagship of the Naval Assault Force Commander. The Deputy Commander V Corps was on board the U.S.S. Charles Carroll and the Deputy Commander First Division on the U.S.S. Samuel Chase. It would have been impossible to accommodate any Army representation on board the Baldwin, and additional facilities had to be installed to provide minimum communications for the Naval Assault Force Commander. Prior to departure from ENGLAND, additional radio sets were installed, additional typewriters, messages blanks and other supplies put on board. A duplicate set of flagship cryptographic publications was put on board in a sealed bag for use if necessary, and a battle bill prepared covering all details of transferring the flag. All personnel were instructed regarding their exact duties in case it became necessary to transfer to the relief flagship.
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Call Signs. Call signs were the most unsatisfactory communication feature in the operation. A large number of call sign books and other references were needed in order to break headings. It was also necessary to decrypt all messages copied as both addressees and delivery instructions were found buried in the text. The advantages in security gained by the use of codress or modified codress must be abandoned in operational communications where speed Is essential. Furthermore, cryptographic errors are impossible to clear when the originator is buried in the text of a message that will not break. A secure call sign system is essential in good naval communications. In this operation call signs indicated by their form the character of the transmitting ship, which is very undesirable for security. Assault and Task Force flagships used two-letter calls, and landing ships and craft used self-evident calls,
A call sign book prepared by the Allied Naval Commander Expeditionary Force was excellent in conception, but too difficult to complete and distribute successfully. In this call sign book (called E.T.O. Call Book) all ships and commands were assigned a call identical in form, consisting of the number 6 followed by three letters. This was good for security, but only one edition was furnished. It was presumably compromised after several days use. However, traffic analysis was made easy by other methods, and it is not believed that the non-changing call signs had any significant effect on the progress of the invasion. The primary defect in the book was that it was incomplete, a condition unavoidable because of the late arrivals in the assault and build-up forces. Last minute changes of commands and units also prevented full use of the E.T.O. Call Sign Book. In combined operations the problem of call signs will always be serious as British and U. S. call systems are radically different in both construction and use. Every effort must be made in future combined operations to solve this problem.
Codes and Ciphers. The provision of adequate cryptographic channels for the operation was complicated by the number of separate services involved, and the large number of small craft which had meager communication facilities. Distribution was also difficult because of the distance between bases, and the impracticability of setting up issuing offices at each base. In view of these handicaps, the small number of errors created by shortcomings in cryptographic facilities should be considered only as lessons learned for the improvement of future operations.
As in some previous amphibious operations, there were too many different communication publications and not enough editions of those most used. r^he enemy opposition encountered extended the assault phase for several days beyond the time usually required. This caused an over use of some publications to the point where they were little better than
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plain language. In the Assault Area of this force, plain language was used to a greater extent than in previous operations, especially on the channels of the low power, frequency modulated SCR-609 radio telephones.
The Combined Assault Code was widely held and proved valuable for sr a-1 craft who do not have facilities for handling a more complicated system. This type of code will not carry much traffic but is extremely useful for a short period. A little practice in its use permitted quick coding and decoding, and a similar publication is recommended for future operations. A garble table should be provided, if necessary, increasing the number of letters in each group to four.
The C.C.M. proved invaluable as a fast and secure method of handling classified dispatches. It is recommended that a cheap and simplified model of this machine be developed for wide distribution to small ships engaged in hazardous waters.
The Hagelin converter was widely used for ship-shore communications, especially by the Army. Several of the machines were captured by the enemy early in the invasion, but no evidence of enemy reaction was noted in this command. The converter gave satisfactory service and continuance of its use is recommended, but limited distribution key lists should be prescribed.
The instructions concerning turning in of excess publications were not clear. This is a matter in which specific directions are essential and nothing must be left to the discretion of subordinate commanders. If a ship is lost in shallow water or compromise becomes possible in other ways it must be known at once what publications were on board. Subsequent checking of reports submitted would take too much time. This is particularly important with regard to reserve editions.
It is believed that most of our ships retained only the June editions, and turned in all later editions. After excess publications had been put ashore, Admiralty issued orders that the July LOXO cards would be used instead of the June cards. This caused considerable confusion as ships officers had to go ashore at the last minute, find their bags of publications, take out the July cards and correct the records accordingly. British ships and craft engaged in the operation did not turn in any publications, but retained full allowances. These circumstances should have been coordinated with our plans so that only American reserve editions would have been put ashore.
World Wide Army-Navy key list for the Hagelin converter was used for the operation and compromised by capture very early. The special key list provided for this operation was not used. It is recommended that whenever special limited distribution crypto channels are provided for certain operations, such channels be used in order to avoid
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compromising widely held channels.
The Army transferred E.C.M. ashore early in the operation, whereas the Navy would not wet up these machines ashore until the front line was over ten miles from the beach. Some agreement should he reached with the Army, regarding the circumstances under which the BCM will he used in the presence of the enemy. Obligatory severe disciplinary action should he required for violation of the agreement.
Assault Communications--Radio silence was maintained by this force until after H hour, as no requirement for radio communication developed before that time. As H hour was well after daylight visual systems were used to the utmost. The primary radio channels for the assault were the FM radio telephones, which were entirely satisfactory. f^heir limited range, and the fact that FM receivers are required to intercept their transmissions, permitted liberal use of plain language. Vague intelligence reports indicated that the Germans were using FM equipment in the same frequency range, but there was no specific evidence of this and no German transmissions were heard on any of our frequencies. The FM crystal controlled portables are superior to any Navy radio sets for amphibious operations.
A bad feature of the assault phase was the fact that the named beaches and the forces using them were not well coordinated. This caused trouble in using the self-evident radio calls for boat wave, control vessels and beachmaster communications. Fortunately the same peculiar arrangement existed in the rehearsal exercise which furnished opportunity for practice. It is recommended that beach names, combat landing teams, boat wave and control vessels be carefully coordinated in order to simplify and improve communications, if for no other reason.
Gunfire support communications were excellent. Model SCR-608 radiotelephones were installed in firing ships and gave good service with the SCR-609 portables used by the Shore Fire Control Parties. HMS GLASGOW reported that the SCR-608 radio set was not as useful as the CW radiotelegraph but this may have been due to technical difficulties.
Several reports have been received which state that the boat wave frequencies were overloaded with unessential conversation. This has been reported in nearly all amphibious operations and may be a psychological phenomenon rather than a communication problem. The ability to t*!k to someone outside your own craft appears to have a good morale effect in time of stress, and the provision of good radiotelephone facilities tends to encourage this.
Beach battalions and shore fire control parties reported that the
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Germans opened fire on them within a matter of seconds if they attempted to use CW radiotelegraph transmissions. They apparently believed that the Germans had some very accurate portable device which disclosed the location of the radiotelegraph transmitter, but the speed at which fire was opened seems to indicate that the Germans used visual observation. The beach battalions, in particular, felt so strongly about this they would not use their CW radios until long after the German batteries had been driven out of range. No attempt was made by the enemy to fire on the FM portable sets, which have very small antennas.
The heavy enemy opposition caused some delay in establishing communication with the beaches. Several beachmasters promptly established communications using their FM radiotelephone, but the setting up of the administrative ship-shore channels using radiotelegraph was delayed longer than necessary. Only two beachmasters (DOG GREEN and EASY RED) established communication by radiotelegraph on D day.
A special information circuit was set up by the V Corps, conforming in general principles with the Air Observer circuit used by Pacific Task Force Commanders* but in this case using four radio equipped DUKWs. Three of the vehicles were knocked out before they could begin operations. A Colonel in the remaining DUKW was assigned the exclusive duty of observing the situation on all beaches and reporting to the Corps Commander in the Amphibious Flagship. In the early stages of the landing the information was of great value to the Navy and similar arrangements are recommended for future operations.
Post Assault Communications.- As is usually the case, it was difficult to determine exactly when the assault phase ended and the post-assault, or build-up phase, began. The plans provided for a Naval Officer in Charge of the Beach area in accordance with British organization, so that all invasion beaches would have similar arrangements for the reception and disposition of convoys in case enemy action made diversion necessary. The Naval Officer in Charge was provided with comprehensive communication facilities to take over full operation of the beaches as soon as the Assault Force Commander was ready to turn over Control. The plans were not carried out promptly. On D plus 12 NOIC OMAHA reported that he was unable to guard the senior officer's broadcast because of lack of personnel. It is believed that the long delay in establishing efficient communications at OMAHA was not due to lack of radio men but primarily to failure of subsidiary plans to provide housing for the apparatus, and quarters and messing for the personnel. In this respect, the British plans were better than ours, as they had made a study of available sites for their shore headquarters and had laid out radio stations and signal stations in detail at selected sites. Future plans should provide at least one Quonset hut for the communication office and equipment of any shore command of the scope of NOIC OMAHA.
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A Combat Fire Fighting and Salvage Unit (CTU-122.3.1) had been attached to Assault Force wOw and was aboard the amphibious flagship. It was realized that the communication requirements of this unit would be considerable, but unfortunately no special provision had been made for them. Improvised arrangements were quickly made regarding delivery and acceptance of traffic and no particular difficulty was encountered, but in future operations it is recommended that a separate radiotelephone circuit be provided for salvage operations.
Communications with merchant ships arriving in regular convoys after the assault phase were not satisfactory, except by visual or messenger. These ships did not hold the communication plan or operation orders, so they did not know the names and locations of the beaches, or frequencies to be guarded. It is desired to emphasize the necessity for thorough briefing of merchant ships sent in subsequent convoys to assault areas, particularly in the arrangements for receiving air warnings and the control of gunfire.
Communication Security, ^he most serious menace to security was the TBS circuit. Efforts to guard conversation were ineffective in most cases, and it must be assumed that the enemy failed to utilize valuable information given him only because he was not prepared to act on it. In particular, information as to the number and type of bombarding ships and the status of their ammunition supply was readily available through analysis of TBS conversations. A serious breach of security noted was the practice of discussing the contents of encrypted dispatches after first identifying the dispatch by its reference number and originator.
Wide latitude was not only permitted but encouraged in the use of plain language on the frequency modulated low power radiotelephone sets. Most of these transmissions concerned matters of immediate importance and it is considered that the sacrifice of security in favor of speed was necessary in effecting success of the invasion. It is recommended that this policy be continued in future operations of this kind.
Some of the widely held cryptographic publications were compromised by capture early in the operation. This contingency must be expected and provided for.
Visual Signals. For reasons of speed and security, visual signalling was used whenever possible. The Assault Area was so large that it was difficult to keep even a rough location sheet of ships and craft within visual range. A communication watch officer was stationed in the flag bridge shelter with a direct telephone connection to the senior C.W.o. in the communication office. This arrangement permitted the senior C.W.0. to decide at once whether to send
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a dispatch visually in plain language, or to encrypt and send it by radio. The bridge C.W.O. also handled all relays, and dispatch replies originated on the bridge. The arrangement proved highly efficient and its continued use is recommended.
A British daylight signalling lantern was obtained just prior to departure for the assault, and installation was completed in the Assault Area. This device proved very useful, and similar installations are recommended for all amphibious flagships.
The shutters in all twelve-inch signal lights in this ship had been turned upside down in accordance with a directive of BuShips to prevent upward transmission of reflected light from the vanes of the shutters. It was decided to accept this possible disadvantage in order to facilitate signalling and all shutters were turned to their original positions prior to the operation. This decision proved sound as it would have been impossible to handle the heavy volume of visual signals with the shutters reversed.
The red filters in the twelve-inch adapters caused some confusion because a flashing red light was the signal for a red air alert, and red signals were also used in some navigational aids. It is recommended that amber or orange filters be used to replace the red. A still better solution would be the use of a signal light with a distinctive orange neon lamp which can be keyed at high speed as there is no "build-up" or "die-down" in intensity. A light of this type was developed by Lieutenant PRASTKAS at H.E.C.P. San Pedro, California in 1941.
Oral Signals. Loud speakers have an extremely valuable application in amphibious communications. The large number of small craft employed can best be handled by oral directions. The loud speakers in the Ancon were low powered portable devices but served the purpose well. It is recommended that amphibious flagships, assault group flagships and control vessels be each provided with a high powered directional loud speaker.
Dispatch Boat Service. The dispatch boat service was well planned and organized, but did not function properly because of the material inadequacy of the boats provided. Nine small twin-diesel-engined boats were transferred from the R.A.F. where they had been used as seaplane tenders. The boats were capable of about 22 knots in calm water but not in the open sea. When received, the boats were in poor mechanical condition and spare parts were almost impossible to obtain. One boat sank before leaving POOLE HARBOR, and by nightfall of D day only one boat was fully operational. The others were running on one engine or had hull damage restricting their use. During the storm of 20-21 June, seven of the remaining eight were destroyed although they were taken out of operation and sheltered inside
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the blockships. A regular dispatch boat service is essential for security and administration, and should he included in amphibious plans, hut adequate "boats should he provided. The 86-foot U.S. Coast Guard boats, which were used after the small boats failed, were excellent for dispatch boat service. High speed is not as essential as reliability.
Air Warnings. A Joint Force Broadcast was established for the purpose of disseminating warnings of air and surface attacks. For security reasons a transmitter was set up in Portland several days before our departure and began regular broadcasts using the Ancon's radiotelephone call. A transmission was made every fifteen minutes to permit ships to keep their receivers adjusted to frequency. These transmissions were continued until some time after the Ancon reached the Assault Area, and began transmitting warnings from the ship. It was not deemed desirable to continue the tuning broadcasts at regular intervals as this would have permitted coordinated radio bearings by the enemy to fix the position of the flagship for instrument bombing. As a further precautionary measure, the berth of the flagship was shifted occasionally just before darkness. The long periods of silence between warnings had a detrimental effect on the force broadcast as receivers would drift off frequency and the short warning broadcasts did not allow enough time for accurate retuning. The frequency allocated for the broadcast (3400 kcs.) was not a good one as it was too high for stability of tuning and was not within the range of the Model RBO broadcast receivers, which many ships could have used for reception. In future operations, if the distance from commercial broadcasters permits, a frequency around 600 kcs. would be more desirable.
A printed poster was prepared and distributed giving the essential features and codewords used in the warning broadcasts. The posters were printed in large type and were intended for display on the bridge or other control location.
Radar Discipline, Guard and Reporting. Orders for radar silence, doctrine and reporting were based on ANCXF's order "ONCO", rather than USF-10A. In view of limited distances and the network of radar stations along the Southern English Coast, radar silence was maintained until surprise was lost as far as air warning sets were concerned, and intermittent use of surface search and fire-control sets was permitted. During the approach, the air situation was maintained by receiving two U.K. broadcasts--the "Home Shore Plots", being a broadcast of about 90 plots per hour of hostile and unidentified planes picked up by shore-based RAF stations in ENGLAND; and the "Air Movements Liaison Broadcast",--a series of predictions of known friendly sorties well in advance of execution.
When air warning silence was broken, only ships equipped with
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SC-2 or SK Radar among U.S. forces were allowed to transmit, plot, filter and broadcast plots over the Naval Radar Reporting WaVe. This limited the use of such type radar to Headquarters ships, transports, battleships and cruisers. Instead of sector sweeps, each Radar guardship (Air) kept a 360° sweep until it detected a target not yet reported over the Naval Radar Reporting Wave. This necessitated each and every ship keeping a close plot, which was not possible aboard the transports because of lack of personnel, and difficult for headquarters ships since there were so many other plots to enter from the broadcasts mentioned above and those following later in the operation. The British, however, used this system to good advantage and it does have points superior to the sector sweep method: -
Accurate information on speed, course and altitude possible since the ship making the report was to keep on target.
Better interpretation from WAW or range scope, than PPI Scopes can give, such as more careful analysis of numbers, maneuvering, and use of WINDOW.
Radar Guardships were still kept advised of the overall air situation, since it was necessary for them to keep the Naval Radar Reporting Wave plot in order to be sure their detections were new targets.
Identification by IFF was difficult since only a limited number of planes could show IFF. Bombers and night fighters kept IFF silence, and only one plane per formation of cover fighters kept this equipment switched on. Ships were directed to use interrogators only when necessary, and discipline on the Ancon was lax in this respect, since the operators were used to continuous interrogation from rapid reading of targets.
The three specially fitted LSTs equipped and manned by the RAF, known as "Fighter Direction Tenders" were the outstanding development for this operation. Fitted with superior RAF radars which could give altitude instantaneously by use of signal-to-noise diagrams, and having a large number of experienced radar, plotting and fighter-direction personnel, these ships furnished the bulk of information to headquarters ships. One V/HF channel was used exclusively as the "Fighter Direction Tender Plots" to broadcast the tenders filtered plots of hostile or unidentified targets, and proved to be the best plotting broadcast of all. Moreover, another V/HF channel known as the "Fighter direction Tender/Headquarters Ship Liaison Wave" allowed follow-up conversation and comparison of information in cases of warning the fleet or directing cover.
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Provisions were made for shore radar stations, "Motile Radar Units", to he set up on the flanks of the overall teach area by D plus one, but only the Eastern British station was contacted over the "Naval Shore Radar Wave*, and then not until D plus four. As an "aid" to security, only obsolete codes and ciphers were used which led to some confusion since most of the ships contacting these stations forgot to keep them, and landed them prior to the operation. The American station had not landed up to D plus fifteen, and for some reason had been sent to SCOTLAND and didn't get off on its proper convoy. No plots were ever heard from these shore stations (eventually to total six), since they were to report only US-boats or low flying planes.
Radio Navigation Aids. The Qfl System proved itself to be the best means of navigation in restricted areas. The set and drift of winds and tide in the channel were such that without this "miniature LORAN", the navigator would have had difficulty in picking up the proper swept channel. Consensus of navigators now is that they cannot do without it, and that it is far superior to radar navigation. The DECCA or QM System, although more accurate theoretically, but not as reliable practically, was successful on the minesweepers because of the proper "phase numbering" possible from check by the Q£ System. In other words, QM is not reliable unless supplemented by QH.
The beacons on the KDMLs stations at the entrance to the swept channels were not up to expectations since the beacons were mounted too low astern. Large swells and the ships swinging caused poor detection ranges.
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From: Commander Assault Force "O", (Commander Eleventh Amphibious Force).
Develop best form and method of preparation of large mounted charts for crypto-channels in code room, and frequency channels in radio room. Provide mounting space and lighting for these charts in amphibious flagships.
THESE AIDS UNDOUBTEDLY IMPROVE THE OPERATING EFFICIENCY OF AN ORGANIZATION, PARTICULARLY WHEN A CONSIDERABLE AMOUNT OF OUTGOING TRAFFIC IS TO BE HANDLED. HOWEVER, THIS IS CONSIDERED TO BE A PROBLEM REQUIRING LOCAL SOLUTION.
Continue use of Combined Assault Code with frequently changing editions.
THEATRE COMMANDERS ARE SUPPLIED WITH ADEQUATE EDITIONS OF THIS CODE. THE INSTRUCTIONS FOR THE USE OF THIS CODE ARE QUOTED IN PART. ... "CONTROL OF DISTRIBUTION, USE, EFFECTIVE DATE, SUPERSESSION, AND DESTRUCTION IS VESTED IN THE SUPREME ALLIED COMMANDER OF THE OPERATION."
Develop and issue simplified model of C.C.M. for small ships.
THE CCM IS CONSIDERED TO BE A HIGH-GRADE CRYPTOGRAPHIC SYSTEM AND ACCORDINGLY IS, IN GENERAL, NOT DISTRIBUTED TO LANDING CRAFT OR TO SHIPS SMALLER THAN FRIGATES (PF). THIS IS IN ORDER TO REDUCE CHANCES OF COMPROMISE, THROUGH CAPTURE, TO A MINIMUM. TO PLACE EVEN A SIMPLIFIED MODEL ON SMALL SHIPS WOULD UNDULY EXPOSE THE SYSTEM TO COMPROMISE. THE CCM ME. I AND MK. II ARE AS COMPACT AND SIMPLE AS PRACTICABLE CONSISTENT WITH REQUIREMENTS OF RELIABILITY AND POWER-OPERATION. IN ANY EVENT, TO DEVELOP, PRODUCE, AND ISSUE A HAND OPERATED MODEL WOULD REQUIRE FROM TWO TO THREE YEARS.
Establish rigid joint agreement with Army regarding use of E.C.M. In hazardous locations.
THE FOLLOWING QUOTATION IS TAKEN FROM "ARMY-NAVY JOINT POLICY CONCERNING DISTRIBUTION AND DISCLOSURE OF CRYPTOGRAPHIC DESIGN OF THE ECM-M134C" (JUNE 26, 1942):
"IT IS MUTUALLY AGREED THAT THE ECM-M134C WILL NOT BE PLACED ASHORE IN FOREIGN TERRITORY EXCEPT AT SUCH PLACES WHERE ARMED PERSONNEL OF U.S. FORCES ARE STATIONED IN SUFFICIENT NUMBERS TO PROPERLY SAFEGUARD THE PHYSICAL SECURITY OF THE MACHINE."
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THE ENTIRE ARMY-NAVY AGREEMENT MAY BE FOUND IN CSPM 182.
SPECIFIC INSTANCES WHEREIN IT IS DEEMED THAT THE E.C.M. HAS BEEN UNDULY HAZARDED, SHOULD BE MADE THE SUBJECT OF A SPECIAL REPORT TO THE CHIEF OF NAVAL OPERATIONS.
Install all-around daylight signalling lights in amphibious flagships.
THIS SYSTEM HAS BEEN INSTALLED FOR SOME TIME IN THE ARKANSAS, NEVADA, AND TEXAS, THE EQUIPMENT HAVING BEEN OBTAINED FROM THE BRITISH.
SINCE ONLY A LIMITED NUMBER OF PERSONNEL ARE FAMILIAR WITH THIS EQUIPMENT, A BRIEF DESCRIPTION IS GIVEN HERE. THE SYSTEM CONSISTS OF TWO 5 TO 6 KW INCANDESCENT LIGHT UNITS, MOUNTED IN AN ELEVATED POSITION, ONE TO STARBOARD AND ONE TO PORT. THE TWO UNITS GIVE ESSENTIALLY 360 DEGREE COVERAGE. THE LIGHTS ARE SHUTTER-OPERATED (8 TO 10 WORDS PER MINUTE) FROM ONE OB MOBS REMOTE KEYING POSITIONS, AS DESIRED. REPORTS INDICATE THAT ON A BRIGHT DAY, SIGNALS CAN BE BEAD, ALL-ABOUND, ABOUT 3,000 YARDS, UNAIDED: WITH BINOCULARS, 5 MILES. ON A DARK DAY, UNAIDED--3 MILES; WITH BINOCULARS 5 TO 6 MILES.
ONE REPORT, FROM THE ATLANTIC, INDICATED THAT BECAUSE VHF RADIO WAS AVAILABLE, THE INSTALLATION OF MOBS OF THESE HIGH INTENSITY SIGNAL LIGHTS WAS UNDESIRABLE. HOWEVER, THERE HAS RECENTLY BEEN A RECOMMENDATION FROM THE PACIFIC THAT FLAGSHIPS BE SO FITTED FOR DAYTIME USE IN LARGE DISPOSITIONS WHEN THE IMPORTANCE OF SPEED OUTWEIGHS THE LOSS OF SECURITY.
UPON RECEIPT OF FINAL COMMENTS AND RECOMMENDATIONS FROM THE ATLANTIC, WHICH ARE EXPECTED SHORTLY, A DECISION WILL BE MADS AS TO WHETHER AN INSTALLATION PROGRAM WILL BE COMMENCED.
Improve filters for signal searchlight adapters using some other color than red to avoid confusion with other flashing red lights.
IT HAS BEEN ASCERTAINED THAT THE CONFUSION MENTIONED ABOVE WAS BECAUSE A FLASHING RED LIGHT WAS THE SIGNAL FOB A "RED" AIR-ALERT, AND BECAUSE RED SIGNALS WEBS ALSO USED IN SOME NAVIGATIONAL AIDS.
APPARENTLY THE SHIP IN QUESTION WAS NOT OUTFITTED WITH THE STANDARD 12" SIGNAL SEARCHLIGHT HOOD WITH COLORED FILTERS. THESE HOODS PERMIT THE USE OF RED, AMBER, AND GREEN. DETAILED INFORMATION ON COLORED FILTERS FOR 12M SIGNAL SEARCHLIGHTS, AND THE PROCEDURE FOR OBTAINING THEM, IS CONTAINED IN BUSHIPS RESTRICTED LETTER. (TO ALL SHIPS AND STATIONS) S66-(l) (3660e)(8660e) EN28/A2-11 DATED 3 FEB. 1943.
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Provide amphibious flagships, assault group flagships, and control vessels with high powered loudspeakers.
THE CHIEF OF NAVAL OPERATIONS IS ENGAGED IN PREPARING AN ALLOWANCE LIST FOR VOICE PROJECTORS FOR ALL TYPES OF LANDING SHIPS AND CRAFT.
Provide special boats (where use thereof is practical) for exclusive dispatch service in Assault Area.
THIS WAS DONE AT NORMANDY AND WHILE THIS SERVICE WAS APPARENTLY WELL PLANNED AND ORGANIZED, IT DID NOT FUNCTION PROPERLY, INITIALLY, BECAUSE OF MATERIAL FAILURES. IN THE LATE STAGES OF THE OPERATION, 86' COAST GUARD BOATS WERE USED WITH COMPARATIVELY EXCELLENT SUCCESS. IT WAS FOUND THAT RELIABILITY WAS OF MORE IMPORTANCE THAN SPEED.
SHORE FIRE CONTROL PARTY COMMUNICATIONS
From: Commander Task Force 129.
Over forty ships of the Western Task Force were equipped with Army radio equipment, SCR 608, for communication with Shore Fire Control Parties. A great deal of the success of the shore bombardment should be laid to this equipment. Shore Fire Control Parties expressed reluctance to use their high frequency keyed circuits, owing to the danger of drawing fire. There was also difficulty in keeping the Army keyed sets (SCR 284) in tune with ships' equipment. As a result, the CW circuits, with the exception of the Common Bombardment Calling Wave, were little used. Although the success of communications with the Shore Fire Control Parties fluctuated, varying with the range and elevative range of the SCR 608 equipment exceeded the range of naval gunfire.
The simplicity and dependability of this equipment recommend it for permanent shipboard installation. A similar model, however, which could be operated from ship's power supply would be an improvement over the Army set which now operates from storage batteries.
Although each ship was initially assigned to one or more Shore Fire Control Parties, it soon became necessary for the Group Commander to coordinate requests for special fire support. In order to do so, he had a separate set of SCR 608 with officers and recorders continuously on watch, and kept a watch on the Common CW Bombardment Calling Wave. It is believed that control of communications by the Bombardment Group Commander, using equipment from that of the Flagship, is essential for the control of fire Involving so many ships and so many spotting parties.
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From: USS Schubrick (DD).
Communications were generally very good, and a great improvement over the Sicilian Operation of a year ago. The SCR 608 FM equipment is excellent for working with Shore Fire Control Parties. Difficulty was experienced because of the large number of parties and ships using each channel. With the number of channels available, (120), it should be possible to have a separate channel for each ship and Fire Control Party. A common channel could be utilized for intercommunication among the various ships and parties. In several instances this ship could not communicate with its Shore Fire Control Party at critical periods because of other traffic on the channel.
From: USS Arkansas (BB).
No difficulties were observed on plane spotting channels. SFCP FM channels were not properly used. Most of the time the common channel was used to carry out a shoot and at times, two shoots were being carried out simultaneously while fire calls were forced to stand by. It is suggested that the controlling station should refuse to allow shoots on this channel unless positively urgent. All shoots must be considered routine unless one becomes necessary above all others In making the operation successful. The present SCR-608 has 10 preset channels which should be sufficient if the operation goes off as planned. However, if an unusual circumstance arises in which the ship and SFCP cannot get together, the ship should be ordered by the controlling station to set up on the SFCP channel. The SCR-608 set can be tuned to one channel in 3 to 5 minutes by an experienced technician without disturbing remaining channels.
From: ComDesDiv SEVENTEEN.
The use of various TBS frequencies successfully prevented overcrowding of that circuit. However, it was found in practice that each Task Force required a separate TBS frequency for its fire-support ships. 8600 KCS worked well as an Area Screen voice frequency. Such a common voice frequency for screening vessels is essential. Communications with shore fire control parties over SCR 608 were excellent.
From: USS Arkansas.
On 14 June, 1944f at 0220 and at 2302B this vessel was attacked by enemy using radio guided missiles, Both signals were located and jammed with missiles dropping harmlessly into the water. Although many signals were heard at times, and guided missiles were reported by lookouts, it is believed these to be the only attacks directed at
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this ship. With jamming signals cluttering up the spectrum, the actual signals were difficult to locate and it is suggested jamming transmitters should not he used or turned on unless a missile is reported in the vicinity. Weak signals should not he jammed when other jamming teams are nearby.
From: ComDesDiv SEVENTEEN.
The "British numbers", long the special aversion of destroyer communication officers in the Atlantic, caused coding boards to fall seriously behind at times. In a future joint operation of similar magnitude, a liaison party, preferably somewhere ashore, to reencrypt and place on broadcast schedules messages which British distribution required to be in numbers, would be well worth the increased traffic,
From: USS Charles Carroll (APA).
If the enemy possessed any radio intelligence organization worthy of the name, he must have been particularly gratified by the results obtained. About a week before D-day two radio circuits were set up within the force which were continually active. While they may have been considered necessary for dissemination of important information, it is noted that in neither of the two exercise operation had these been set up. ^he enemy might have drawn some highly accurate conclusions as to the imminence of D-day. Furthermore, an exercise radio circuit was set up prior to sailing in which all transports participated, thus revealing through call size patterns the size of an important part of the force. Exercises a week before the invasion are too late to train radiomen.
Another major criticism which was made generally by all communication personnel was of the method in which the signal to postpone D-day twenty-four hours was promulgated. As set up in the Operation Plan it consisted of "POST M ONE", which on at least one circuit was put out in plain language. The obvious importance of this signal as indicated by its being repeated several times on various circuits would certainly appear to warrant the enemy making the not unreasonable assumption that D-day had been postponed one day and that he could look for trouble on a near following day.
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