The practical methods by which the Navy and its brave mine-trawlers conduct their operations are of great interest, but description cannot go too far. The enemy is certainly well acquainted with all British methods previous to the war; but mine-sweeping systems do not stand still, but develop with the progress of armaments generally. Mine-trawling is developed from the system of trawling for fish, which before the war had reached a high degree of technical efficiency, and in the application of that system to their work in the war the men have attained great proficiency and become extraordinarily successful. The trawl-net varies in size with the dimensions of the vessel using it. An average size would be about 100 feet in length, with a spread of from 80 to 90 feet. The principal features in fishing trawlers are fore and after frameworks, with fairleaders, a towing-block, a powerful steam-winch, and towing-warps. A trawler would pay out hundreds of fathoms of heavy wire warp, the handling of which called for great skill and dexterity. It was not a very difficult thing to adapt this method of trawling to the sweeping for mines. The fishing trawler goes unaided, but in mine-sweeping the trawlers work in pairs, and the towing-warp is replaced by the sweeping-wire. Two trawlers, steaming abreast at a certain interval, drag a weighted steel hawser which, upon striking the mooring of a mine, brings the deadly catch to the surface, where it is exploded by gunfire from a destroyer or by rifle fire from an armed trawler or motor boat. The mine-sweepers have encountered perils and hardships which have never been recorded, and fishing trawlers pursuing their peaceful occupations have often incurred the same risks. Next after the destruction of the enemy’s fighting vessels comes the destruction of his death-dealing mines, and the mine-trawlers, confronted with an unparalleled task, attended with extreme peril, have rendered magnificent service to England and her Allies. CHAPTER VII THE NAVY AND ARMY TRANSPORT What of the mark? Ah! seek it not in England; A bold mark, an old mark Is waiting over-sea; Where the string harps in chorus, And the lion flag is o’er us, It is there our work shall be. _Sir A. Conan Doyle._ The stupendous and scarcely calculable operation of transporting by sea the enormous armies which are employed in many theatres of the hostilities is the index and measure of the greatest of all the triumphs of naval power in the war, namely, that of establishing and maintaining essential command of the sea. Against this bulwark the enemy’s naval forces have battled in vain. The submarine may, in some degree and in some circumstances, affect command of the sea, but it cannot exercise it.