Few except sailormen can realise the dangers and anxieties of navigation in times of war. The absence not only of the warning lights which in days of peace flash their signals far out over the seas, marking the innumerable dangers which lie along treacherous coasts, but also of warships and merchantmen rushing through the night with not even the flicker from a port-hole to denote their coming--perhaps at a speed of nearly three-quarters of a mile a minute; a second's indecision on the part of the brain and nerve directing each ship, a momentary forgetfulness of that elusive "right thing to do"--some second danger to attract a flash of attention from the first--even a blinding cloud of spray at the psychological moment and, well, two more ships have gone, with perhaps hundreds of lives. Yet these things but seldom happened, and the reason was that all that tireless energy, skill and nerve could do was done on the sea in those years of storm and stress. Some two hours later, and just before dawn broke over the tumbling sea, an exceptionally heavy wave struck the trawler full on the port-bow. The hammer-like blows of the water as it poured on board and struck the base of the wheel-house and superstructure momentarily drowned all other sound. When the air had cleared of flying spume a big black hull loomed out of the darkness ahead and seemed suddenly to grow to an immense size, towering high above the trawler's forecastle-head. A blast on the whistle, a sharp order and the trawler swung off to starboard, with the great black mass perilously near. It was a close shave, and the watch held their breath while waiting for the crash and shock which for a brief second seemed inevitable. There was no time for action or signal. The great ship slid past like some black phantom framed in the white of flying scud. It faded into the misty darkness of sea and sky almost as quickly as it had appeared, and, curiously, no sound of throbbing engines accompanied its passage. It took the captain of the patrol but a minute to make up his mind what to do. He gave a quick order to the helmsman and a warning shout to the watch below on deck. The little ship, as she came about, lurched into the trough of a sea and rose shivering from end to end. The next moment an avalanche of white and green water poured over her, flooding the decks and sending clouds of spray high over the funnel and masts. Then commenced an exciting chase, with the seas racing up astern and all eyes trying to penetrate the darkness ahead. The faint misty light of a new day had brightened the eastern horizon before the mysterious ship again loomed up ahead. The heavy sea still running made it difficult, however, to distinguish any national or local characteristics which might give a clue to her identity or intentions, and the suspense was keen.