During the years 1916 and 1917 the Belgian ports of Zeebrugge and Ostend had become more and more important to the Germans as a base for their submarines. Their loss would be, as Admiral Scheer said, "a very disagreeable blow to the U-boat campaign." It was in November 1917 that the British Admiralty first planned a blow against these ports, but the favourable opportunity did not present itself until April 23, 1918. In the meantime, the Allies had succeeded in bringing the last German offensive to a standstill, and there was much anxiety as to its possible renewal. The blow struck by the Navy on St. George’s Day was therefore a most timely one, for it not only increased Admiral Scheer’s difficulties but resounded over the world as a daring feat of arms and a proof of unbroken national spirit. The difficulties of the proposed attack were enormous, and real imagination was needed to cope with them. The coast was defended by batteries containing in all 120 heavy guns, some of them of 15-inch calibre. A battery of these was emplaced upon the Mole at Zeebrugge—a solid stone breakwater more than a mile long, which held also a railway terminus, a seaplane station, a number of large sheds for personnel and material, and, at the extreme seaward end, a lighthouse with searchlight and range-finder. The attacking force would also have to reckon with the batteries on shore, the troops who would reinforce the defenders on the Mole, and the destroyers which were lying in the harbour. It was not, of course, proposed to take and hold works so strongly defended; but an attack was indispensable, for the enemy’s attention must be diverted from the block-ships, which were to arrive during the fight off both ports and sink themselves in such a position as to impede the passage of U-boats. The offensive then was directed against Zeebrugge, and the plan of attack was to be the seizure of the Mole by a landing party. They must be strong enough to overrun it, capture the big guns, and keep off enemy reinforcements by destroying the railway viaduct which connected it with the shore. Then, when the block-ships had been sunk, the men must be re-embarked and brought away.