The foregoing chapters have been devoted to describing the measures that were devised or put into force or that were in course of preparation during the year 1917 to deal with the unrestricted submarine warfare against merchant shipping adopted by Germany and Austria in February of that year. It now remains to state, so far as my information admits, the effect of those measures.

British anti-submarine measures were almost non-existent at the commencement of the war. Sir Arthur Wilson, when in command of the Channel Fleet in the early days of the submarine, had experimented with nets as an anti-submarine measure, and shortly before the war submarines were exercised at stalking one another in a submerged condition; also the question of employing a light gun for use against the same type of enemy craft when on the surface had been considered, and some of our submarines had actually been provided with such a gun of small calibre. Two patterns of towed explosive sweeps had also been tried and adopted, but it cannot be said that we had succeeded in finding any satisfactory anti-submarine device, although many brains were at work on the subject, and therefore the earliest successes against enemy submarines were principally achieved by ramming tactics. Gradually other devices were thought out and adopted; these comprised drift and stationary nets fitted with mines, the depth charge, decoy ships of various natures, gunfire from patrol craft and gunfire from armed merchant ships, as well as the numerous devices mentioned in Chapter III.

Except at the very commencement of the war, when production of craft in Germany was slow, presumably as a result of the comparatively small number under construction when war broke out, the British measures failed until towards the end of 1917 in sinking submarines at a rate approaching in any degree that at which the Germans were producing them.

Thus Germany started the war with 28 submarines; five were added and five were lost during 1914, leaving the number still 28 at the commencement of 1915.

During 1915, so far as our knowledge went, 54 were added and only 19 were lost, the total at the commencement of 1916 being therefore 63.

During 1916 it is believed that 87 submarines were added and 25 lost, leaving the total at the commencement of 1917 at 125.

During 1917 our information was that 78 submarines were added and 66 lost, leaving the total at the end of the year at 137.

The losses during 1917, given quarterly, indicate the increasing effectiveness of our anti-submarine measures. These losses, so far as we know them, were:

During 1918, according to Admiral Scheer ("Germany's High Sea Fleet In the World War," page 335), 74 submarines were added to the fleet in the period January to October. The losses during this year up to the date of the Armistice totalled 70, excluding those destroyed by the Germans on the evacuation of Bruges and those blown up by them at Pola and Cattaro. Taken quarterly the losses were:

It will be seen from the foregoing figures for 1917 and 1918 that the full result of the anti-submarine measures inaugurated in 1917 and previous years was being felt in the last quarter of 1917, the results for 1918 being very little in advance of those for the previous half-year.

According to our information, as shown by the figures given above, the Germans had completed by October, 1918, a total of 326 submarines of all classes, exclusive of those destroyed by them in November at Bruges, Pola and Cattaro.

Admiral von Capelle informed the Reichstag Committee that a total of 810 was ordered before and during the war. It follows from that statement that over 400 must have been under construction or contemplated at the time of the Armistice.

It is understood that the number of submarines actually building at the end of 1918 was, however, only about 200, which perhaps was the total capacity of the German shipyards at one time.

At the risk of repetition it is as well to repeat here the figures giving the quarterly losses of merchant ships during 1917 and 1918, as they indicate in another and effective way the influence of the anti-submarine measures.

These figures are:

The decline of the losses of British shipping was progressive from the second quarter of 1917; in the third quarter of 1918 the reduction in the tonnage sunk became very marked, and suggested definitely the approaching end of the submarine menace.

The fact that during the second quarter of 1918 the world's output of tonnage overtook the world's losses was another satisfactory feature. The output for 1917 and 1918 is shown in the following table:

It will be noticed that by the last quarter of 1918 the output of shipping in the United Kingdom alone had overtaken the losses of British shipping.

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.