Admiral Henry T. Mayo, Commander, Atlantic Fleet, Standing Order
S E C R E T
UNITED STATES ATLANTIC FLEET
5 December 1917.
STANDING ORDER NO. 5.
SUBMARINE OFFENSIVE; DOCTRINE.
1. Under present conditions vessels of the Fleet are divided into two categories with relation to the offensive against submarines:-
(1) NON ANTI-SUBMARINE VESSELS:
(a) Battleships and armored cruisers,
(b) Transports and hospital ships,
(c) Supply ships, fuel ships, repair ships, cargo carriers.
(2) ANTI-SUBMARINE VESSELS:
(a) All other vessels of the Fleet.
2. The vessels of category (1) are not by their characteristics fitted for offensive operations against submarines. Further, the immediate missions of the types in this category are as follows:
(1) (a) Battleships and armored cruisers: To maintain themselves in readiness for efficient action against enemy surface craft; primarily against corresponding types.
(b) Transports and hospital ships: to safely transport personnel and material.
(c) Supply, fuel, repair ships and cargo carriers: to maintain lines of communication and furnish supplies and material to the fighting forces.
3. The vessels of category (2) are either fitted by their characteristics, or must at present be utilized, for the offensive against the submarine. Further, their immediate mission is the destruction of enemy submarines and safe-guarding and protection of ships of category (1) and of ships of the merchant marine in addition.
4. Vessels of category (1) shall avoid action with enemy submarines and shall only take the offensive against submarines when that course appears to offer the best means of successful self protection.
5. Vessels of category (2) shall at all times search out and take the offensive against enemy submarines, except when on escort duty, in which case the protection of the convoy shall be considered paramount and the destruction of enemy submarines secondary, e.g. – escorting vessels shall attack any submarines whose position threatens the convoy, but shall not leave the convoy to pursue offensive action against a distant submarine unless the remaining escort vessels are considered sufficient to protect the convoy temporarily.
6. Vessels of category (1) – (a), Battleships and armored cruisers, will from time to time be used as ocean escorts to convoys. When on such duty the paramount mission becomes the protection of the convoy and escorting vessels shall take such offensive action against submarines as may be necessary to accomplish the mission.
7. It is probable that enemy submarines will make use of false distress calls to entice vessels within gun or torpedo range.
8. Vessels in company shall take no action on distress calls received other than to forward them by visual signal to the Senior Officer Present, who shall make decision as to further action to be taken. In making his decision the Senior Officer Present shall be guided by the following rules:
First: Vessels of category (1) should not proceed to the vicinity of a distress call.
Second: Vessels of category (2), unless other considerations prevent, should proceed immediately to the vicinity of a distress call, as whether the call is true or false such action will be in accordance with their mission as given above.
<9. The Senior Officer Present shall if practicable forward the distress call by despatch to vessels of category (2) in the vicinity, the nearest shore station, and the Commander in Chief, bearing in mind the inadvisability of disclosing the position of his own forces by use of radio and the possibility of an enemy ruse made for that purpose.>