Over on the opposite side of the river stretches a long quay. The background of it is a naval railway station; the ships lying in front of it are partly supply ships, partly merchant vessels brought in under convoy, and two of them are depot ships, moored permanently there, and used as headquarters for the Submarine, Destroyer, and other services. Out in the centre of the harbour lies a still larger depot ship, the floating headquarters of the Admiral who is Commodore of the port; and behind her, in two long lines, stretching away upstream into the far distance, lies an apparently inexhaustible force of light cruisers, destroyers, and destroyer-leaders, with here and there a submarine--one is slung aloft in a dry-dock for overhauling. A side creek to the left is crowded with trawlers and drifters, whose men are now ashore ‘between sweeps.’ At this hour of the day the place is at its fullest, for the daily ‘Beef Trip,’ or food convoy, has just come in, and the dozen destroyers which escorted it are all lying at their moorings, on both sides of the main stream line. There they will be till to-night, when at 7 o’clock to the second they will all slip away again into the twilight like thin grey ghostly dogs, shepherding another flock of very substantial sheep.
The trawler puts us aboard the depot ship; but the Admiral is not there. A picket-boat takes us over to his pier, and we find him in his chart-room, surrounded by maps marked with spots and figures in different colours, quite unintelligible except to those who have the key, and even to them no subject for conversation at large. But the Admiral is a good talker, his mind is an encyclopædia of submarine war and the working of a naval base, and he is amazingly quick in separating the facts which interest you, and yet are fit for repetition outside, from those which you must forget as soon as you have heard them. He begins by explaining the daily routine of the port--the mine-sweeping, which is done regularly twice a day, but at what times the enemy can only guess, and the mine-laying, which is a game of brain against brain, each side trying to see through the other’s devices and catch him with their own. An elementary example would be the obvious dodge of moving the enemy’s mine a short distance, instead of removing it altogether--so that when next he comes that way, he shall run into it unexpectedly, and perish by his own trap. But this, as I have described it, is too simple a device to be successful, and the ingenuity of our mine-layers has improved upon it by a dozen skilful variations. Much can be done by studying carefully the habits of the German mind. One officer, who is specially skilled in this matter, has the credit of being able to make a U.C.-boat lay her eggs just where he pleases, and of knowing exactly when it will be time to go and collect them.