Still, we were unarmed. If, by zigzag and a keen look-out, we were fortunate in evading torpedo attack, the submarine had by now mounted a surface armament, and we were exposed to another equally deadly offence. For our protection, Admiralty placed a new type of warship on the routes approaching the channels. Built originally for duty as minesweepers, the sloops were faster and more heavily armed than the drifters. They patrolled in a chain of five or six over the routes that we were instructed to use. During the daylight hours we were rarely out of sight of one or other of the vessels forming the chain. Our route orders were framed towards a definite point of departure into the high seas when darkness came. There, the patrol of the sloops ended: we had the hours of the night to make our offing and, by daybreak again, were assumed to be clear of the 'danger zone.' But the 'danger zone' was being extended swiftly; it was not always possible to traverse the area in the dark hours of a night: only the fast liners could stretch out a speed that would serve. Profiting by experience that was constantly growing, the _Reichsmarineamt_ constructed larger submarines capable of remaining long at sea, and of operating in ocean areas that could not adequately be patrolled. Twelve, fifteen--then twenty degrees of longitude marked their activity advancing to the westward: they went south to thirty-five: in time the Mediterranean became a field for their efforts. Gunfire being the least expensive, they relied on their deck armament to destroy unarmed shipping. The patrols were but rarely in sight; the submarine became a surface destroyer. There was no necessity for submergence on the ocean routes: under-water tactics were held in reserve for use against fast ships--the slower merchantmen were brought-to in a contest that was wholly in favour of the U-boat. In a heavy Atlantic gale, _Cabotia_ was sunk by gunfire, 120 miles from land. She had not the speed to escape. Despite the heavy seas that swept over the submarine and all but washed the gunner from the deck, the enemy was able to keep up a galling fire that ultimately forced the master to abandon his ship. _Virginia_ was fired upon at midnight when steering for the Cerigo Channel. Notwithstanding the courage of Captain Coverley, who remained on board to the last, there could be but one end to the contest. _Virginia_ was sunk. A strong ship; the enemy had to expend two of his torpedoes to destroy her.