That Germany made a bold bid for triumph cannot be gainsaid. There were times when the Allied Admiralties regarded the situation as critical. The statistics of the matter are instructive, though not pleasing. From first to last Great Britain lost 9,000,000 tons of shipping, while Allies and neutrals suffered to the extent of a further 6,000,000 tons. In addition there were eighty British vessels, with an aggregate tonnage of 172,554, held up in German ports during hostilities, an amount by no means to be despised, although it is small compared with the enemy tonnage captured and brought into Allied service. The latter reached the respectable figure of 2,392,675. British naval casualties totalled 39,766 in killed, wounded, interned, and captured. In the Merchant Service 14,661 lost their lives, and 3,295 were taken prisoners. War in the Underseas was waged at frightful cost to all belligerents, both vanquished and victors. Taking British losses by enemy action and marine risks during the war, the worst quarters were in this order: second quarter of 1917, third, first, and last quarters of the same year, and first quarter of 1918 and last quarter of 1916. In April 1917, 555,000 tons of British shipping were sent to the bottom. Had things gone on at that rate, “we were in deadly danger; had it gone on for nine months we were ruined.”[34] In September 1918 the depletion had been reduced to 151,000 tons. Captain Persius asserts that, following the action off the Danish coast, twenty-three battleships were disarmed for the purpose of obtaining metal for constructing U-boats—excellent proof of the grip of the blockade and of the British victory at Jutland. His figures regarding underseas craft are a little difficult to follow, because he only deals with what he calls ‘front submarines,’ presumably those definitely on active service and not merely patrolling in home waters. In April 1917, he says, Germany had 126 U-boats, in the following October 146; in February 1918 she possessed 136; in June of the same year, 113. In January 1917 only 12 per cent. were at sea, 30 per cent. in harbour, 38 per cent. under repair, and 20 per cent. incapacitated. His most important admission is that the ill-trained crews had no confidence in their craft, and that toward the end of the campaign it was difficult to get men to work them. He flatly contradicts the assertion that losses were made up by new construction. Apart from the offensive operations of the Navy proper, the defensive equipment of traders and the introduction of the convoy system in the summer of 1917 were of enormous importance in thwarting the submarine. In addition to merchant shipping and munitions 16,000,000 fighting men were escorted, and of these less than 5000 met with disaster.