It is not possible to give exact information as to the particular means by which the various German submarines were disposed of, but it is believed that of the 186 vessels mentioned as having been lost by the Germans at least thirty-five fell victims to the depth charge, large orders for which had been placed by the Admiralty in 1917, and it is probably safe to credit mines, of which there was a large and rapidly increasing output throughout 1917, with the same number—­thirty-five—­a small proportion of these losses being due to the mines in the North Sea Barrage.  Our own submarines accounted for some nineteen.

Our destroyers and patrol craft of all natures sank at least twenty by means of gunfire or the ram, and some four or five more by the use of towed sweeps of various natures.  Our decoy ships sank about twelve; four German submarines are known to have been sunk by being rammed by men-of-war other than destroyers, four by merchant ships, and about ten by means of our nets.  It is fairly certain that at least seven were accounted for by aerial attack.  Six were interned, some as the result of injury after action with our vessels.

The total thus accounted for is 156.  It was always difficult to obtain exact information of the fate of submarines, particularly in such cases as mine attack, and the figures, therefore, do not cover the whole of the German losses which we estimated at 185.

CHAPTER X

“PRODUCTION” AT THE ADMIRALTY DURING 1917

The anti-submarine measures initiated during the year 1917 and continued throughout the year 1918, as well as those in force in the earlier years of the war, depended very much for their success on the work carried out by the Admiralty Departments responsible for design and production, and apart from this these departments, during the year 1917, carried out a great deal of most valuable work in the direction of improving the efficiency of the material with which the vessels of the Grand Fleet and other warships were equipped.

Early in 1917 certain changes were made in the Naval Ordnance Department.  When Captain Dreyer took up the post of Director of Naval Ordnance in succession to Rear-Admiral Morgan Singer on March 1, the opportunity was seized of removing the Torpedo Department, which had hitherto been a branch of the Naval Ordnance Department, from the control of the Director of Naval Ordnance, and Rear-Admiral Fitzherbert was appointed as Director of Torpedoes and Mines, with two assistant Directors under him, one for torpedoes and the other for mines.  It had for some time been apparent to me that the torpedo and mining work of the Fleet required a larger and more independent organization, and the intention to adopt a very extensive mining policy accentuated the necessity of appointing a larger staff and according it greater independence.  The change also relieved the D.N.O. of some work and gave him more liberty to concentrate on purely ordnance matters.