Against eventual landings, the defences also comprised a series of mine barrages, screens of nettings for submarines, hindering the access of the shore. Redoubts manned by infantry troops were staking out an almost uninterrupted line of trenches which were running along the beach, right up to the Dutch frontiers. Machine-guns and field guns were utilized for flanking the strand and for anti-aircraft action. The German defence of the Belgian coast was completed by high sea forces. The organization of the maritime defences was only seriously taken in hand in 1915. The “Boat-detachement” composed of trawlers, mine sweepers, tow boats and barges, was formed up in February that year. Small types of torpedo-boats and submarines were sent dismounted, and conveyed by railway up to the dock-yards created at Bruges, Ostend, and later on at Hoboken, where those units were mounted. They formed with a certain number of other units which came directly by sea, a flotilla of submarines and one of torpedo-boats. Motor trawlers were on the watch far out in the sea. In 1916, the naval forces anchored in the Flanders base were considerably increased in number, but it was particularly in the year 1917 that the Germans multiplied their submarines, thus turning the harbours of Ostend and Zeebrugge into real haunts. Shelters were built to protect them against air raids and the numerous bombardments carried out by the British Fleet. At Zeebrugge, the shelters were established along the mole and in the tidal basins south of the locks and in the Bruges canal. At Ostend, the flotillas were berthed in the wharfs and the darses. The submarines were sheltered alongside the marine docks. The year 1917 saw the submarine warfare ruthlessly carried out and the enemy’s torpedo-boats raided the British and French coast. In the early 1918, during the dismal winter nights, the foe undertook several offensive reconnoitrings up to the British Channel. These were to be their last deeds. Doggedly determined to bring an end to the U boats’ boundless crimes, the British Admiralty tackled the plan for the bottling up of the two Belgian harbours. It was thus that were performed the most astounding operations, which took the enemy unaware, pinning him down in Zeebrugge and almost paralysing him in Ostend. ⁂ “=Kaiser Wilhelm II battery=” constitutes one of the typical kind of heavy battery erected by the Germans along the North-Sea. _Armement_: Four 12 inch marine guns, firing at 38 kilomètres (23½ miles) a shell weighing more than 400 kilos, needing a charge of 103 kilos. The tube was 17 meters 25 cm^s long. _Gun crew_: 5 officers and 360 other ranks. _Observation-posts_: especially in Knocke’s Kursaal and on the down 23 near Duinbergen. _Ammunition supply_: was done by railway. _Historical account_: the battery was armed in July 1916 but did only fire during our Flanders offensive in 1918.