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Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to Rear Admiral Albert P. Niblack, Commander, United States Patrol Squadron Based at Gibraltar



30 Grosvenor Gardens,


Reference No. 01.19445.

31 May, 1918.           

From:   Force Commander.

To:     Commander, Patrol Squadrons Based on GiBraltar.

Subject:  Speed of Ships in Convoy.

Reference: (a) Your cable 889 of 25 May.1

     1.   Reference (a) recommends that American merchant vessels carrying armed guards be fitted with a few depth charges. The subject of having merchant vessels fitted with depth charges has been under consideration a number of times, and has always been rejected owing to the small likelihood of the merchant vessels being in a position to deliver an effective attack with depth charges. It has also been suggested that bomb throwers be installed in merchant vessels, and this has been rejected for similar reasons. Installing depth charges in a merchant vessel required trained personnel to carry out the necessary safety precautions, and while in a few cases it might be advantageous for merchant ships to have depth charges, these cases are rare and do not warrant a general policy of installing depth charges in merchant ships.

     2.   Reference (a) also recommends that vessels of 11 knots’ speed or more be routed independently in the Mediterranean. This recommendation is not concurred in by the Force Commander. While it is unfortunate that vessels of speed must travel in slow convoys, there are many advantages to sailing ships in convoys. Even with the poorly protected convoys in the Mediterranean it is noted that the loss does not exceed 2%, and on the convoys between Gibraltar and Genoa the loss is only 1.5%. This loss compares very favorably with the losses in Atlantic convoys, which are about 1%.

     3.   All experience shows that submarines prefer to attack single ships rather than attack convoys under escort, even altho the escort be a weak one. Eleven knots’ speed is not sufficient to make it particularly difficult for submarines to deliver effective attacks. For several months large, fast vessels leaving England, having speeds as high as 17 knots were routed independently until three of these ships were sunk, since which time all of them have been included in convoys. A speed of 11-knots cannot assure for a ship any considerable degree of immunity. Experience shows that vessels routed alone fail to zigzag, show lights, disregard route instructions, or take other measures that generally defeat some of the advantages in proceeding at full speed.

/s/ WM. S. SIMS.             

Source Note: Cy, DNA, RG 45, Entry 517B. For the 1st Endorsement of this letter, see: Niblack to Sims, 14 June 1918.

Footnote 1: The document referred to has not been found, but for more information on depth charges and merchantmen, see: Niblack to Sims, 28 May 1918.