In due course 4.1–in. guns, mounted on disappearing platforms, made their _début_, followed by U-boats provided with two 5.9–in. guns. With increase of gun-power came a necessary increase in size, and with both several distinct advantages and disadvantages. The boats were less easy to manœuvre, required augmented crews, and offered a larger area for attack. Against these minus qualities must be set those of increase of cruising range, and the possibility of spoil, the sole excuse of the old-time pirate. Hitherto his more scientific successor could only sink his victim. Now, given favourable conditions, he might carry off goods useful to the Fatherland. One German U-boat secured twenty-two tons of copper from merchantmen destroyed during a 5000–mile cruise. Germany waxed particularly enthusiastic over her diving cruisers. These boats displaced 5000 tons, were from 350 feet to 400 feet long, had a much accelerated submerged and surface speed, were protected by an armour belt of tough steel plate, and mounted a couple of 5.9–in. guns. Some of these submersibles seem to have been driven by steam when in surface trim, others by the usual Diesel engines. On the 11th May, 1918, a British Atlantic escort submarine came across one of these fine fellows travelling awash, likely enough anxious to have a shot at the merchant convoy which the representative of His Majesty’s Navy was on her way to pick up. A heavy sea was running at the time, but at intervals between the waves the periscope revealed the position of his rival to the British commander. One torpedo sufficed. The _Tauchkreuzer_ went down, carrying with her the sixty or seventy men who constituted her company. There were no survivors. She had the distinction of being the first of the type to be destroyed. Germany’s merchant service, prizes of war, or driven off the seven seas and growing barnacles in neutral or home ports, virtually ceased to exist at the outbreak of hostilities. The mammoth liners which formerly competed with our own no longer sailed the seas with their holds full of cheap goods and their saloons alive with travellers bent on ‘peaceful penetration’—and other things. It rankled in the bosoms of her shipping magnates that the much-vaunted High Sea Fleet was impotent to prevent Britain ‘carrying on’ commercially while conducting campaigns in all parts of the world. It was true that Germany’s U-boats were making inroads on the maritime resources of her enemy, that when hostilities were over they might compete on more than even terms because of these losses, but to-day rankled though to-morrow was full of hope. Likewise the Economic Conference in Paris had declared its firm intention to impose special conditions on German shipping after the war. _After_ the war! The Director-General of the North German Lloyd Line said that the English were not so unpractical as to reject a favourable freightage or passage.