Chapter II
Routing, Reporting and Control of Independents since 7 December 1941


It can be seen from Chapter I, D that the organization of independent ship control was progressing slowly prior to 7 December 1941, but with the country explosively awakened to a precarious situation, and with our substantial ocean-going merchant fleet of some 8,500,000 gross tons further exposed to attack, the central organization in the Navy Department itself and the assignment of overseas representatives began to develop rapidly. The policy of the Navy Department was and is to cooperate fully with the various agencies concerned with shipping operations. In Washington, C&R provides the War Shipping Administration with information regarding ship movements, and advises it in the light of current enemy operation as to the most economical employment of merchant tonnage. In the field, the routing or reporting officers cooperate to the fullest extent possible with representatives of the W.S.A. and, insofar as sound security measures permit, civilian shipping interests. Early information is indispensable to these agencies for proper harbor arrangements, rapid docking and cargo handling which are the prerequisites of efficient ship operation.102



1. With war declared it became apparent that a more detailed agreement was necessary as regards the methods of routing, reporting and diverting merchant ships and convoy movements, particularly to attain international uniformity and understanding. In February 1942 representatives from the Trade Division of the Admiralty and Naval Services Headquarters, Ottawa, met in Washington and developed a combined worldwide routing agreement known as the "British-United States Routing Agreement" (short title "BUSRA"). It was approved by the Commander in Chief and concurred in by the Admiralty on 1 March 1942. This common plan was based largely on the existing system, which was operating satisfactorily after two years of wartime use by the British Empire.

2. As a result, the British publication, "Mercantile Atlantic Routing Instructions" (short title MARI) was promulgated to all U.S. Routing Officers In the Western Atlantic Area. A publication containing Western Atlantic coastal routing instructions, "Mercantile Atlantic Coastal Routing Instructions" (short title MACRI) was prepared by C&R and was distributed to Routing Officers in the Western Atlantic area North of Commander, FOURTH Fleet's area as well as to diverting authorities. In addition, a single routing directive for the Pacific "Mercantile Pacific Routing Instructions" (short title MPRI), comprising both U.S. and British Routing Officers in the Pacific Ocean Area. This publication superseded a previous manual, "Mercantile Pacific Coastal Routing Instructions" (short title MPCRI), which was used for U.S. West Coastal Routing.51 53 54 81 102



1. On 1 July 1942 full responsibility for the policy of routing, reporting and evasive diversion of independents in U.S. areas was assumed by F-371 under the direction of F-37. This fundamental development in the affairs of C&R is described in detail in Cominch C&R's dispatch of 11 July to all Sea Frontier Commanders, NOB Trinidad and CAFAC, part of which is herewith paraphrased.202

"Cominch assumed entire control and protection by routing and diverting of merchant shipping in U.S. strategic areas on July first. The Convoy and Routing Section is charged with performance of these duties. Control is maintained through Sea Frontier Commanders and Port Directors to Routing Officers within the Sea Frontiers and through designated ALUSNAS, ALUSNORS, ALUSLOS, CSA's and seacoast AMCOMS in the U.S. strategic areas, all of whom comprise the Merchant Ship Control Service organization." This dispatch then goes into the details of the relations set up between C&R and the Sea Frontier Commanders in the routing and diverting of convoys and independents through the Sea Frontier areas.

2. In the Atlantic, where most shipping was in convoy throughout the war, routing was governed by the terms of a joint publication, MARI. Amendments thereto were proposed by either C&R or Admiralty for approval by the other. In coastal areas, however, routing was determined by the terms of MACRI, changes in which were promulgated by C&R after conferring with or on recommendation from the Sea Frontier Commanders. In the same manner the British entirely controlled coastal routing in the Eastern Atlantic. Similarly, routing in the Pacific was under U.S. and in the Indian Ocean under British control.53 54


Because of the overlapping and duplications of instructions appearing in these various publications, C&R prepared for the U.S. representatives in the field and put into effect "General Instructions to Routing and Reporting Officers" (short title "GIRO") on October 15, 1942. It was later rewritten and promulgated as GIRO-1944 on January 13 1944 in conjunction with "Wartime Instructions for Merchant Ships" (WIMS). Together with MARI, MPRI, etc. and serial or dispatch directives, GIRO constitutes a complete and comprehensive picture of what the Navy Department expects of the U.S. Merchant Ship Control Service. In the area of British responsibility, the Naval Control Service operates with "Naval Control Service Instructions" and area routing publications, in addition to Admiralty and station Commander directives.51 52 54 64 70


1. The field personnel required for the operations of FX-371 were the Port Directors and Routing Officers in areas controlled by U.S. Commanders. Overseas, rapid development of operations was made possible by the far-sightedness of the Directors of Naval Intelligence who had made provisions for the placing of U.S. Navy Representatives throughout the world as early as 1940 in the capacity of Naval Observers, whose duties were not only to collect intelligence but also assist in the control of U.S. merchant ships. These duties were later expanded so that in our areas of responsibility they involved routing and reporting of all United Nations vessels and liaison with American masters in the ports under British strategic control. As time went on, merchant ship control service officers were separated to some extent from O.N.I. personnel and placed under the personnel officer of the Naval Transportation Service.


2. In addition, arrangements were made with the State Department for up to 40 American Consuls in our areas of responsibility to assume additional duties under the Navy Department of reporting movements in smaller ports where the volume of shipping was too limited to warrant the assignment of Naval Officers. In certain South American and Russian ports where it was impossible to arrange for U.S. Naval representation, Consular Shipping Advisors were assigned as assistants to the Consuls for reporting purposes.

3. In accordance with BUSRA the Navy retained Routing Liaison Officers in the principal ports under British Control for the purpose of contacting American masters in connection with routing and security matters. The British have retained in our principal ports British Liaison Officers for similar work. Officers so assigned in the United Kingdom under COMNAVEU were known as U.S. Navy Port Officers.57 102


In Chapter I, G 2 the general duties of the Assistant Director of C&R were set forth. In addition the following principal functions are performed by officers under his supervision. 102 108 201

1. Independent Plot (FX-3711)

1. This sub-section immediately under the Assistant Director was originally titled "Merchant Plotting" (Op-37-1-M, later F-3711 and then FX-3715), and has duties defined in most organization charts as:

  1. Maintain world-wide plot of all independent merchant vessel movements.
  2. Primarily responsible for diversion of independent vessels in Western Atlantic Area.
  3. Maintain liaison with F-21 (Combat Intelligence - Atlantic) for the purpose of obtaining current information on enemy activity. (see Appendix Q)

2. Prior to March 1942 the section's chief function was merely to plot and keep a record of the number of ships at sea in the Atlantic and Pacific. In the case of the North Atlantic daily dead reckoning positions were based on a grid system used jointly with British and Canadian authorities. However, no action was taken by U.S. authorities to divert ships from enemy danger, all diversions being made by the British, except that coastwise shipping was controlled by the Sea Frontier commands.

3. After BUSRA was promulgated C&R assumed control of independent shipping west of the "CHOP" line. This general diversion of operational control has continued ever since with certain modifications, and this headquarters in Washington has been responsible for the control of all merchant shipping west of the chop line. In practice, however, the various Sea Frontiers usually act in connection with traffic inside their own areas.

4. Large wall charts, one of the North Atlantic and one of the South Atlantic,


are maintained, showing the situation at sea as of 1200Z of the current day. By means of different tabs and pins, distinctions are made between independent Allied ships, Allied convoys, Allied submarines, enemy submarines and surface raiders, storm centers, collisions, strandings and the like. (see Appendix PP and Appendix QQ).

5. Independent Allied ship positions are determined on the basis of the routing instructions issued to a ship for each independent voyage made by it, a copy of which is received by this headquarters through its own communication center. The pertinent information from the data issued by the routing offices is assembled by the respective plotting officers. This information is then turned over to a quartermaster, who draws the actual route for the ship in question on a piece of tracing paper placed over a copy of a chart adopted for use in this section (Strategic Plotting Chart H.O. No. 5050-28). This is done to enable coordination wit the information regarding enemy activity, as will be explained later. The 1200Z dead reckoning position for each day of the voyage is shown on the route, the coordinates of these positions in turn being transferred to a mimeographed form. All information for the current voyage of each ship is thus made available in one place and amendments to the route, based on diversions by the various authorities, position reports radioed in by the ship itself, local weather conditions, plane spottings, contacts at sea, and the like, can be readily made, thus keeping an up-to-date record for the duration of the ship's voyage. These folders are retained for about three months and then destroyed.

6. Allied convoy dead reckoning positions are based primarily on information supplied by the Convoy Plot Section. This is supplemented, however, through details furnished by the Admiralty and COMNAVEU.

7. Allied submarine positions are based on the latest details supplied by the various interested commands. This information is shown on the plot because it is necessary to keep friendly shipping away from our own submarines and at the same time warn the latter of the presence of merchant vessels.

8. Enemy submarine and surface raiders are shown on the plot on the basis of the most accurate information available through Combat Intelligence. (see Appendix OO)

9. Inspection of the two wall charts, after they have been set for the current day, enables the Section Officer to determine whether any independent ships are adjacent to the estimated areas of enemy activity. If so, the route information for the merchant vessel in question is broken out, the tracing paper copy of the route being superimposed on a Strategic Plotting Chart on which the current operational areas of enemy activity have been drawn. Inspection will also indicate whether any diversions are required to keep independent shipping well clear of convoys, thus minimizing the risk of collision. If it is deemed necessary, action will be taken to amend the ship's route so that it will pass well clear of the danger zone. Such a diversion is effected by means of a radio message or BAMS (Broadcast to Allied Merchant Ships) to the ship in question, transmitting the amended route positions or other pertinent information.

10. A secondary function of the plot has been to redirect ships enroute from one destination to another as may be required by the War Shipping Administration, the Trade Division of the Admiralty, or the British Ministry of War Transport. Liaison is maintained with representatives of these organizations, enabling prompt action to be taken either by BAMS from this headquarters or through the various Sea Frontiers, thus minimizing the steaming time of vessels at sea when such changes are required.

11. A third wall chart, comprising both the North and South Atlantic, is maintained to indicate the daily 1200Z position of neutral ships at sea. Neutral


shipping is required, for the most part, to follow certain prescribed routes agreed upon by both the Allied and Axis powers. Furthermore, daily radio position reports are required from neutrals in certain areas and a fairly accurate dead reckoning plot can be kept. At the height of enemy submarine activity in the Atlantic area the plot was of use in determining whether or not "neutral" shipping was aiding the Axis by refueling or supplying submarines and raiders at sea. At present its primary function is to show the flow of traffic and to aid in the preparation of operational summaries indicating the position of neutral ships at sea. (see Appendix TT)

12. In addition to the strategic Atlantic areas, other wall charts are maintained for the Pacific and Indian Ocean areas. Since these are not of an operational nature, but serve to indicate general routes and traffic trends, they are set only twice a week rather than daily. For a period, a worldwide chart of all tanker positions was kept for general information. (see Appendix RR and SS)

13. The wall charts aid in the preparation of various operational reports. Typical is the daily message to Bermuda informing that activity of independent shipping in its air patrol area, as well as the bi-weekly report giving the position of neutral ships west of 26°W, addressed to the interested commands. Photographs are taken of each wall chart after it has been set and the negatives are in turn filed so that a complete historical record is available. In addition prints are furnished to Anti-Submarine Warfare Operational Research Group (ASWORG) for use in connection with statistical studies. (see Appendix OO to Appendix TT inclusive).

14. Insofar as convoys are concerned, a pin for each ship in the convoy is mounted on the wall under a tag labeled with the convoy title, enabling a ready determination of the name, flag and type of each ship and assisting in studies of operational moves and supply trends.

15. Separate from the wall charts, small boards are maintained for each of the principal Allied and neutral ports throughout the world showing, by means of individual ship pins, vessels currently due or actually confirmed in port. Positions of these pins are based on information received from the various reporting centers and indicate not only just what ships are in port, but the general trend of shipping, areas of congestion, and similar details. (see Appendix NN).

16. The duties of the Independent or Merchant Ship Plot were being performed as of April 1945, by 4 officers, of whom 2 are WAVES, and 7 enlisted personnel.

17. Lt. Commander R. N. Norgaard, USN, was in charge of the Merchant Plot Section until April 1943, when he was relieved by Lt. Commander C. S. Boarman, USN (Ret), who in turn was relieved by Commander E. W. Whitehead, USN (Ret), in September 1943.

18. The following table shows in detail the number and location of 9,641 merchant ships and U. S. Naval Auxiliaries just prior to VE Day as reflected by the wall charts and plot boards of FX-3711. The following qualifications should be noted regarding the figures shown therein:

a. In general the ship pins represent only those carried by the Merchant Ship Records Section (FX-3712), namely all U.S. vessels of 1000 gross tons and over, all Allied and neutral vessels (excluding Turkish) 1000 gross tons and over operating in the hemisphere, all Allied and neutral vessels (excluding Turkish) 2000 gross tons and over, regardless of area of operation, and USS Auxiliaries of certain types (AE, AF, AH, AK, AKA, AKD, AKS, AO, AOG, AP, APA, APD, APH, APM, APN, APR, APV, IX).


b. The wall charts do not show every ship known to be at sea as of 1200Z for the current day. For example, local shipping in the Canadian Coastal Zone, independent or escorted, does not normally appear on the chart. This is generally true of other areas insofar as local trips of a few days duration are concerned, the ship pins being placed in the due section of the "in port" board for their respective destination. In addition, reports regarding shipping are sometimes received after the movement has taken place, too late to be shown at sea on the respective wall charts. An illustration of this is the fact that the accompanying table indicates only 22 ships in convoy in the Pacific area. The total in convoy was actually much higher by the time complete reports for that period were received. (see Appendix RR).

c. No plot is maintained of ships at sea in the Mediterranean and Black Sea area, the ships merely being moved from on port board to another on the basis of information supplied by the shipping control authorities throughout the area, the voyages being of short duration.


(see Appendix PP to Appendix TT inclusive)

                     Neutral FlagD  
  U.S. FlagB USSC Brit. Flag Foreign Flag USSR Other


Atlantic Area
At Sea (Independent) 203 9 86 62 0 91 451
At Sea (In Convoy) 453 5 241 134 0 0 833
In Port (Due or Confirmed) 1282 72 1188 551 7 265 3365
Local TradeA              
British IslesE 0 0 148 31 0 0 179
East Coast North AmericaF 60 0 0 0 0 0 60
CaribbeanG 6 0 12 34 0 0 52
East Coast South AmericaH 0 0 0 73 0 26 99
Mediterranean ApproachesI 0 0 0 0 0 71 71
Total Atlantic 2004 86 1675 885 7 453 5110
Pacific Area              
At Sea (Independent) 546 49 42 29 29 3 698
At Sea (In Convoy) 16 4 0 2 0 0 22
In Port (Due or Confirmed) 1234 492 194 95 217 3 2235
Local TradeA              
West Coast North AmericaJ 32 0 3 0 0 0 35
Australian AreaK 0 0 73 16 0 0 89
Total Pacific 1828 545 312 142 246 6 3079
Mediterranean and Black Sea Area              
At Sea (Independent) Not Plotted
At Sea (In Convoy) Not Plotted
In Port (Due or Confirmed) 195 2 240 73 2 25 537
Local TradeA L 4 0 55 153 0 0 212
Total Med. and Black Sea 199 2 295 226 2 25 749
Other Areas (Indian Ocean, etc.)              
At Sea (Independent) 35 0 67 18 0 0 120
At Sea (In Convoy) 0 0 0 0 0 0 0
In Port (Due or Confirmed) 76 2 432 68 0 5 583
Total Other 111 2 499 86 0 5 703
Grand Total 4,142 635 2,781 1,339 255 489 9,641



  1. Vessels in local trade or shuttle service are not shown on the wall charts as being at sea since their voyages are of short duration, are wholly within one local area or their movements are not normally reported.

  2. Includes also Panamanian and Honduran flag vessels under U.S. Control.

  3. Includes only those types of auxiliaries normally carried by the Merchant Ship Records section of FX-37.

  4. Argentine vessels are included in the category of neutrals, their present status being such that they are not considered eligible to receive secret and confidential publications normally issued to Allied vessels, nor to travel in convoy with other Allied shipping.

    USSR vessels are also included in the category of neutrals, the majority of this shipping being in the Pacific Area and classed as such.

  5. Includes:
    1. Ships trading locally within the British Isles.
    2. Merchant ships in His Majesty's Service (serving as Naval Auxiliaries) the location of many of these not being known definitely, but presumed to be in home waters.

      Note: This is NOT a complete tabulation of all ships so employed, but includes only those carried by the Merchant Ships Records Section of FX-37.

  6. Includes vessels trading locally in the area between Hampton Roads and the Gulf of Maine.

  7. Includes tankers operating locally to and from Aruba, Curacao and Lake Maracaibo as well as adjacent areas.

  8. Includes 73 Brazilian vessels operating locally between ports in that country as well as 26 Argentine vessels employed locally between ports in Argentina and adjacent areas.

  9. Includes vessels operating locally between Spanish, Portuguese and North West African ports as well as the adjacent island possessions.

  10. Includes vessels trading locally in the area between San Diego and Vancouver - Victoria, B.C.

  11. Includes vessels trading locally between Australian ports.

  12. Includes vessels trading locally between ports in the Mediterranean.


19. Of the 9,641 ships plotted on this day, 4,777 or 50% were of U.S. Flag, including Naval Auxiliaries.


20. Of the total, 53% were in the Atlantic, 32% in the Pacific, 8% in the Mediterranean and Black Seas, and 7% in the Indian Ocean.

21. Excluding the ships in local trade, 6,720 or 76% were in port, the balance of 2,124 being at sea. Of those at sea 1,269 were independent and 855 in convoy. Actually, however, it is probable that the proportion in convoy was substantially higher, for reasons stated.


1. The first records of merchant ship movement were based on reports passed from the ship owners through W.S.A. to Op-38-0 a month or so in advance of proposed sailings. After early in 1942 the Marco reporting system provided more detailed and up-to-date information, safeguarded by the wartime security of the naval communication system. Upon Op-37 being set up, all ships were card-indexed and plotted daily by three separate units, American (37-1-MA), British (37-1-MB) and Foreign (37-1-MF). The Foreign Plot Sub-Section originally was staffed primarily with 21 ONI personnel, who in addition to functioning as a unit of C&R performed normal duties in connection with Naval Intelligence.102 201

2. In December 1942 the Merchant Ship Records section was separated from the Independent Plot. Its duties under the Director and Assistant Director are specified as follows:

  1. Maintains card file of the movements of merchant vessels and Naval Auxiliaries and other pertinent information.
  2. Keeps liaison with cognizant Government agencies on ship movements and other pertinent information.
  3. Maintains ship casualty records.
3. In order to shift, interpret and summarize all the information received via dispatch from shore commands, ships at sea and escort commanders, three sub-divisions are in operation, as below.

a. Ship Movements: Here is kept a record of each ship in an alphabetical card file. In this "piano", at it became known, is entered the sailing date, port of departure, convoy designation if in convoy, and arrival date and port of each ship. All casualty information is written in, as well as diversions, detachments and changes of destination. After being entered in the piano, the data is logged, and copies thereof distributed to those concerned in C&R, WSA, Op-20-M (Postal Affairs), and in the case of tankers, Op-05-P (Materiel), and Petroleum Coordinator for War (Department of Interior).

b. Casualties: This section compiles a daily report of the essential details of all ship casualties, whether by marine cause or enemy action. This information, after being recorded in the piano, is distributed daily to other sections of C&R and to the President, Secretary of the Navy, Chief of Staff TENTH Fleet, Bureau of Personnel (Casualties), F-21 (Combat Intelligence), FX-43 (Anti-Submarine Warfare Analysis), Op-20-R (Communications), Op-20-M-4 (Naval Postal Affairs), Army Postal Service, and O.C.T. (Army). Weekly and monthly summaries are distributed to Army, WSA (Casualty Section), Bureau of Personnel (Casualties), Op-16-P1 (Intelligence) and Op-16-B2 (Counter Intelligence).

c. Convoys: A record is made of every convoy except British coastals, listing all ships therein by name, the convoy sailing date and port, destination, estimated time of arrival, speed [of] escort vessels, Commodore's ship and references to pertinent dispatches. A separate sheet is typed for each convoy


and filed by convoy designation. Any changes subsequent to sailing are entered in the piano and on the permanent file copy. This convoy data is distributed to C&R sections and to WSA, Op-20-M, Op-05-P, Op-39-T-2 (Traffic), Allied Tanker Coordination Committee OCT (Army), ONI and British Admiralty Delegation.

4. As of March 1945 the files of FX-3712 contained records of approximately 9,160 merchant vessels and 720 Naval Auxiliaries afloat. On an average, 1,089 entries per day were being made on the cards and an equal number in the log. This work was being performed by 7 officers, of who 5 were Waves, and 8 enlisted Wave personnel.701


1. From the time when the Convoy and Routing Section was first organized the Assistant Director has required the services of certain officer personnel acting as Staff Assistants. During the period of creative work immediately following our entry into the war, these Staff Assistants consisted of one Captain, USN; two Commanders, USN; and five junior reserve officers.

2. Captain John T. Bottom, Jr., USN, supervised the work of the Records and Plot rooms and handled a part of the general liaison work. Commanders Robert O. Strange USN, and Richard G. Visser, USN, created and were in charge of all routing publications, and assisted in general policy matters concerning the routing of independent ships.

3. As time went on and the work became more routine the number of Staff Assistants was gradually reduced. In April 1944 the Records and Plot Rooms were placed under the direct supervision of the Assistant Director. During the next six months, the number of junior Staff Assistants was reduced from five Reserve Lieutenants to two, both of whom had been in the Section since early in the war and were thoroughly familiar with the work. This number proved to be satisfactory during the closing months of the war. 102 201 (see Appendix Q).


1. One of the major functions of C&R has been the controlled routing of independent ships. Throughout the war certain classes of ships have continued to run independently even where convoys were available. In general, these were ships of speeds less than 8.0 knots that were not qualified for most convoys, or ships of over 14.5 knots whose very speed made independent routing a justifiable risk. In many ports of the world, however, ships of all speeds have been routed independently throughout the war only because no escorts have been available.

2. Two basic policies were adopted in independent routing varying with the areas involved. For coastal traffic, standard routes were established shortly after the outbreak of the war. These routes, in general, were close inshore and were designed to force U/Boats to enter the more dangerous coastal waters. Standard routes also have the advantage of channeling traffic into fixed lanes, which reduces the possibility of collision, a major hazard throughout the war because in most areas ships stream without lights. While standard routes have the disadvantage of localizing shipping so that U/Boats, once in the lane, find many targets, it was


found that close inshore routing of coastal traffic was more effective defense against U/Boats than divergent routing which is necessarily limited in confined waters.

3. In transoceanic shipping, however, the emphasis was placed on diversified routing wherever sea-room made it possible. Every effort was made to scatter independent shipping throughout any given ocean area, avoiding peacetime steamer tracks and standard turning points which could have been made the focal point for enemy attacks. After the establishment and extension of the coastal convoy system from Canada to Brazil, almost no independent ships of less than 14.5 knots sailed in the Western Atlantic during the height U/Boat warfare in 1942 and 1943. However, no convoy system was ever established between South America and Capetown, and when the enemy found that practically all shipping north of Natal was being convoyed, he shifted his efforts to the South Atlantic where many slow independent vessels were lost attempting to reach the Persian Gulf and the Red Sea via the Cape of Good Hope with cargoes that were so vital at that early stage of the war. To combat the serious threat to what was then a most important supply route, it was decided that the greatly increased steaming distance and heavy storms off Cape Horn, all independent shipping destined for the Indian Ocean from the North American east coast was routed via the Panama Canal, the west coast of South America via Cape Horn to South African ports for onward routing into the Indian Ocean. This route was used by more than 200 independent ships during the last four months of 1942.

4. When the enemy moved a sizeable concentration of U/Boats to the area off Capetown to attack this shipping, it was again decided to accept the increased distance and heavy headwinds in the South Pacific. The vital flow of war materials was accordingly re-routed to proceed from Panama by an approximate great circle route south of New Zealand to Freemantle in Western Australia for onward routing. This course proved to be entirely safe except for negligible losses from Japanese submarines operating in the Indian Ocean. Over 500 independent ships made this voyage before the route was discontinued following the opening of the Mediterranean to convoys in July 1943. Such a method of handling shipping destined for the critical Red Sea and Persian Gulf areas is a good example of what can be accomplished by the controlled routing of independent ships.

5. Another interesting case of independent routing took place on the Iceland-Murmansk route. German attacks on North Russia convoys by coordinated aircraft and U/Boats caused such heavy losses that the convoy system was abandoned during the summer months of 1943, when continuous daylight made it impossible for the convoys to avoid immediate detection. The political and military situation made it absolutely essential to continue some for of traffic onto the northern Russian ports during that summer. Accordingly, a plan known as the "Trickle Movement" was adopted, and independent ships were routed through a most dangerous area where usual routing was the only protection. These independent ships were routed through the extreme northern waters of the Greenland and Barents Seas. The plan was not entirely successful, but 50% of the independent ships so routed made safe arrivals in north Russian ports, whereas the last convoys to make the run in 1942 had lost one-half to two-thirds of its ships. The Trickle Movement was a temporary expedient taken previously because of the importance of maintaining a token flow of shipping to north Russia. It was abandoned after a short period when it again became possible to reinforce the escorts of the North Russian convoys to the point of reasonable safety.

6. After the summer of 1943 the U/Boat threat in the South and West Atlantic


was greatly lessened. The convoying of all ships became an unnecessary waste of valuable ship days, and a fluid policy of sailing ships of various types and speeds independently in those areas not currently threatened was adopted by C&R. Here again divergent routing was used wherever possible until the threat had so diminished that it became preferable in 1944 to establish standard routes between such points as New York and Windward Passage and on to Panama and Trinidad. As stated before, these standard routes have the advantage of almost eliminating the danger of collision, an ever present hazard that must be considered in all routing.

7. In late 1944 and 1945 C&R adopted the basic policy of independent routing for tankers of all speeds and for dry cargo ships of speeds of 10 knots and over. The dry cargo ships of 8 to 10 knots were retained in convoys not so much for their protection as to form a nucleus for the maintenance of a convoy system which would be available for all shipping should the enemy threat return, which in matter of fact it did during 1945. This policy was designed to reduce the loss of ship days inherent in any convoy system. Experience gained through the acid test of war has established beyond a doubt that a most important problem in merchant ship control is to strike a proper balance between risk and delay, in determining policy of convoys versus independent routing. It has been shown that effective and relatively safe control of large movements of independent shipping can be attained through constant vigilance and a fluid policy which meets the constantly varying conditions of warfafe.102 108 201


1. In the spring of 1942 the Commander, Western Sea Frontier, as principal Shipping Control Authority in the Pacific under WPSC-46, submitted recommendations to C&R for two routing publications, Mercantile Pacific Routing Instructions (MPRI) and Mercantile Pacific Coastal Routing Instructions (MPCRI). With minor modifications, these directives were prepared and issued in mimeograph form by C&R (then Op-37). On 20 January 1944 the two were combined into book form by C&R as MPRI-1944, which then became the main Pacific routing directive.

2. In February 1944 Commander in Chief, U. S. Pacific Fleet was designated as the principal Merchant Ship Control Authority in the Pacific and assigned associated duties in connection therewith as specified in MER-1. This development, coupled with an escort shortage and the need closer control of the ever expanding shipping in the central and forward Pacific Areas, brought CinCPac into a position of predominance over routing affairs in that area.

3. During 1944, with the assignment to CinCPac's Headquarters of personnel experienced with shipping control in the Atlantic, still further decentralization from Washington was accomplished. CinCPac was authorized to amend or change MPRI without clearing all matters through C&R. On 16 August 1944 C&R became merely the distributing medium through Registered Publication Memoranda of MPRI amendments as promulgated by CinCPac.94 In September CinCPac published a Pacific Routing Directive as a Pacific Fleet Letter to replace MPRI. Finally, on 1 May


1945 Wartime Pacific Routing Instructions (WPRI), written and distributed by CinCPac, became the principal Pacific routing publication and MPRI was cancelled, removing C&R from all direct connection with policy matters concerning Pacific ship control.

4. Nevertheless, the plotting of independents and convoys as well as the recording of all ship movements in the Pacific were being maintained as usual up to VE Day, as described in section F of this chapter.


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