Sortie and Entry
1100. The purpose of sortie and entry plans is to provide for the orderly departure or entrance of a large number of vessels from or into a port with the greatest possible security.
Section I. General
1101. Sortie or entry is made under any one of the following conditions or combinations of some of them:
- No enemy opposition of any character.
- Opposition from enemy mines.
- Opposition from enemy submarines.
- Opposition from enemy light forces.
- Opposition from enemy heavy ships.
- Opposition from enemy aircraft.
In addition to the above, opposition from enemy shore batteries may be encountered during entry.
1102. The plan to be used for sortie or entry is one suitable for the task organization and for the conditions to be encountered during the operation. Type plans are available in appropriate publications. Standard plans are practicable when there is no opposition of any character or when there is only opposition from mines and submarines. Standard plans are usually prepared well in advance. Special plans or operation orders are necessary when sortie or entry is made under other conditions. The nature of the port, the depth of water after clearing the entrance, the navigation channels and the number of entrances or channels are considerations that require a modification of standard plans.
1103. Prior to departure from or entrance into a port held by our own forces, if any opposition from enemy mines, submarines, or aircraft is possible, preliminary measures to contribute to the success of the operation are taken as much in advance as is necessary by the base defense force, or any other force in the port that is free to do so. These preliminary measures are:
- Scouting by aircraft, surface vessels, or submarines.
- Patrolling the area outside the harbor entrance to prevent the laying of enemy mines and to detect and destroy enemy submarines.
- Sweeping of the navigation channels to deep water or specified lanes to deep water.
- Marking of such channels by buoys or by range marks.
- Maintaining constant radar watch on both surface and air search radar apparatus.
- Maintaining constant watch on underwater detection apparatus.
1104. If the force is not restricted as to the course it takes, the preliminary sweeping operation is not confined solely to the one lane to be used, in order not to divulge to the enemy by the sweeping operations the lane that will be used. Unless otherwise prescribed, swept channels are 500 yards wide.
1105. Immediately prior to the operation, the forces at the port:
- Establish an air patrol over the area to be used by the force.
- Make a final sweep of the channel to be used.
- Take measures to have all friendly submarines clear of the area to be used by the force in order that any submarines encountered may be considered hostile.
1106. The required Conditions of Readiness for action and Material Conditions to be assumed by individual units are, unless otherwise prescribed by the officer in tactical command, as set forth in current fleet publications.
1107. Sortie and entry procedures depend upon the task organization, geographical considerations, and probability of enemy opposition.
1108. Channel formations for sortie or entry are prescribed by task force commanders.
1109. The use of high speeds in passing through a narrow navigation or swept channel decreases the time to maneuver to avoid a ship mined or torpedoed. On the other hand, the use of low speeds in a narrow navigation or swept channel which is exposed to air or submarine attack increases the chance of ships being hit by bombs or torpedoed in those confined waters. In addition, low speeds in a narrow navigation or swept channel increases the time required for sortie or entry and thereby increases the possibility of submarine and air attack during a period when the ships are unusually vulnerable to such attacks.
1110. The senior officer present after a base has been occupied issues standard instructions regarding:
- The channels to be used.
- The channels or areas to be swept for enemy mines.
- The extent of the area to be searched and patrolled.
- The point or points of origin at which cruising or other dispositions will be taken.
Special instructions for sortie from and entry to a particular port are issued by the controlling authorities of that port.
1111. The purpose of sortie plans is to provide for the orderly departure with the greatest possible security of a large number of vessels from the same port so that they may readily take a cruising disposition or be in a suitable disposition to meet the enemy outside the port.
Section II. Sortie
1112. Sortie plans prescribe the sequence of leaving port and the interval between task subdivisions in relation to the zero hour. They prescribe the speed to be used in the channels and, if enemy opposition is to be expected, assign appropriate tasks to the various task subdivisions. The operation order under which the force proceeds to sea includes among its provisions the sortie plan to be used, the time of zero hour, the course, speed, and disposition to be taken at the point of origin.
1113. If submarines are operating as a task subdivision of a force they normally clear the harbor first and sufficiently in advance of zero hour to be well clear when the surface vessels leave and to screen ahead of the force while it is taking the prescribed disposition. The light forces, aircraft carriers, battleships, and train normally follow in the order named. If opposition from enemy submarines, aircraft or surface vessels is probable during sortie or just after clearing the port, the officer in tactical command disposes his forces so as to best repel the attack. In this case, the train may remain in port until the situation clears.
1114. If vessels are not required to keep in a navigation or swept channel upon clearing the entrance to the port and if the only probable attack after clearing the port is one from submarines, it is necessary for the heavy vessels and train vessels to use the highest practicable speed until well clear of the entrance. The distance between vessels under these circumstances may be increased.
1115. Responsible commanders may order a sortie of their forces from port when an air attack is imminent. All vessels make preparations for getting underway when warning of approaching enemy aircraft is received.
1116. The purpose of entry plans is to provide for the orderly entry of a large number of vessels into the same port so that they may take up their assigned anchorages readily; to provide for overcoming enemy resistance at the port and to provide security to heavy ships and train while they are taking their station in the disposition for entering port and during the time their movements are restricted by the necessity of conforming to navigation or to swept channels.
Section III. Entry
1117. Entrance is always made under one of the following situations:
- Port is held by our own forces.
- Port is not occupied by own or enemy forces.
- Port is held by the enemy.
1118. Consideration is given to the time of entrance in order that adequate investigation may be made after daylight and in order that sufficient hours of daylight remain to make the entry.
1119. When little is known concerning a port, reconnaissance is made by verifying occupation by enemy or to ascertain enemy's strength or dispositions if enemy is present.
1120. The order in which the task subdivisions approach and enter the port depends upon circumstances. If there is no opposition from the enemy of any character, the order of entry may be the order in the cruising disposition, or it may be a different one if more convenient for taking assigned anchorages. If the force itself sweeps the entrance for mines and keeps enemy submarines down, the vessels assigned this task proceed in advance of the rest of the force. If the force is being harassed by enemy surface ships or aircraft, measures are taken to cover the entry of any noncombatant types.
1121. The commander of a task force prescribes the order of his task subdivisions. The sequence in which they proceed depends to a great extent upon the relative position of their berths in the anchorage plan.
1122. Unless directed otherwise, antisubmarine screening ships patrol the area on the flanks and off the outer end of the navigation or swept channel. They leave their stations and enter as directed in the plan, normally after all heavy units have entered.
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