In April, 1916, a net barrage, with lines of deep mines on the Belgian side of the nets, had also been laid along the Belgian coast covering the exits from the ports of Ostend and Zeebrugge as well as the coast between those ports. These nets were laid at a distance of some 24,000 yards from the shore. This plan had proved most successful in preventing minelaying by submarines in the Straits of Dover, and the barrage was maintained from May to October, but the weather conditions had prevented its continuance from that date. The operation was repeated in 1917, the barrage being kept in position until December, when the question of withdrawing the craft required for its maintenance for patrol work in connection with the minefield laid on the Folkestone-Grisnez line came under discussion. The Belgian coast barrage being in the nature of a surprise was probably more useful as a deterrent to submarine activity in 1916 than in 1917. In both years a strong patrol of monitors, destroyers, minesweepers, drifters for net repairs, and other vessels was maintained in position to the westward of the barrage to prevent interference with the nets by enemy vessels and to keep them effective. These vessels were patrolling daily within 13 or 14 sea miles of the two enemy destroyer and submarine bases, and although occasionally attacked, were not driven off in spite of the superior destroyer force which the enemy could always bring to bear. In 1917 actions between our vessels and those of the enemy, and between our own and enemy aircraft, were of very frequent occurrence. The Germans also introduced a new weapon in the form of fast motor boats controlled by a cable from the shore and guided by signals from aircraft, these boats being heavily loaded in the fore part with explosives which detonated on contact with any vessels attacked. On only one occasion in four attacks were the boats successful in hitting their mark, and the monitor _Terror_, which was struck in this instance, although considerably damaged in her bulge protection, was successfully brought back to port and repaired. Whilst our monitors were on patrol near the barrage, as well as on other occasions, every favourable opportunity was taken of bombarding the bases at Zeebrugge and Ostend. In the former case the targets fired at were the lock gates, and in the latter the workshops, to which considerable damage was frequently occasioned, as well as to vessels lying in the basin. These bombardments were carried out in 1917 at distances exceeding 25,000 yards. The long range was necessary on account of the net barrage, and also because of the rapidity with which the "Knocke" and "Tirpitz" shore batteries obtained the range of monitors attacking them, one hit on an unprotected monitor being sufficient to sink her.