The Germans had always built their small craft rapidly, although their heavy ships were longer in construction than our own. Their destroyers were completed in a little over twelve months from the official date of order in pre-war days. During the early years of the war it would seem that they maintained this figure, and they succeeded in building their smaller submarines of the U.B. and U.C. types in some six to eight months, as U.B. and U.C. boats began to be delivered as early as April, 1915, and it is certain that they were not ordered before August, 1914. The time taken by the Germans to build submarines of the U type was estimated by us at twelve months, and that of submarine cruisers at eighteen months. German submarine officers gave the time as eight to ten months for a U-boat and eighteen months for a submarine cruiser. (It is to be observed that Captain Persius in a recent article gives a much longer period for the construction of the German submarines. It is not stated whether he had access to official figures, and his statement is not in agreement with the figures given by German submarine officers.) It is of interest to note here the rate of ship production attained by some firms in the United States of America during the war. As I mention later (_Vide_ Chapter vi, p. 157), the Bethlehem Steel Company, under Mr. Schwab's guidance, produced ten submarines for us in five months from the date of the order. Mr. Schwab himself informed me that towards the end of the war he was turning out large destroyers in six weeks. The Ford Company, as is well known, produced submarine chasers of the "Eagle" type in even a shorter period, but these vessels were of special design and construction. I have dealt so far with the question of anti-submarine measures involving only the use of destroyers and other small surface craft. There were, of course, other methods both in use and under consideration early in 1917 when we took stock of the situation. For some time we had been using _Decoy vessels_, and with some success; it was possible to increase the number of these ships at the cost of taking merchant ships off the trade routes or by building. A very considerable increase was arranged. The use of our own _submarines_ offensively against enemy submarines had also been tried, and had met with occasional success, but our numbers were very limited (the total in December, 1916, fit for oversea or anti-submarine work was about forty). They were much needed for reconnaissance and offensive work against surface men-of-war in enemy waters, and only a few were at the time available for anti-submarine operations, and then only at the cost of other important services.