Vice Admiral Sir Cecil F. Thursby, R.N. Commander-in-Chief, Plymouth, to Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters
19th September 1918.
My dear Admiral,
Many thanks for your letter and the enclosures. As regards the papers on submarine hunting, I thoroughly agree with the general principles that should govern the employment of Submarine Chasers, and think that the organization and tactics recommended are thoroughly sound.
They are practically the same as those adopted by our own hunting flotillas.
I should like to offer the following remarks as regards their application to suit the conditions in the Plymouth Command:
In regard to organization, owing to the excessively bad weather which is usually prevalent in the mouth of the Channel during the winter months, I do not think that these vessels can act far afield, as they must always have a base within reasonable distance where they can run for shelter at short notice. This limits their activities outside the Channel to the vicinity of the Scilly Islands and the North Cornish Coast – both places much frequented by enemy submarines.
The best organization would therefore seem to <be> divide them into three squadrons, each consisting of one or more divisions of four units, one squadron to use Scillies and Cornish ports as bases; the second squadron to operate further up the Channel,using Plymouth as a base and the Channel ports from Falmouth to Torquay as ports of refuge; the third squadron to be at the base resting and refitting. The duties should be arranged so that the squadrons are employed in rotation at each place.
As regards tactics, the first and most important thing is to get in touch with an enemy submarine. In order to do this the “Communications” must be perfected, and the closest co-operation established between the various sources of intelligence, both at Headquarters and the War Signal and War Watching Stations along the coast. Also, close touch must be maintained with the Aircraft, who, in addition to finding the submarine and reporting his position, should take part in the attack, in co-operation with the submarine chasers. Unfortunately, the activities both of the Submarine Chasers and the Aircraft are limited by weather conditions, and although the Chasers can remain at sea for some time after flying is impossible, their listening apparatus are not much use in a heavy wind and sea.
This has been well illustrated during the past week by the operations of enemy submarines in Lyme Bay, and on the North Cornish Coast, when the weather was too bad for flying, and small craft had to take shelter.
Cecil F. Thursby.