Already in November 1914 the Germans began with the fortification of the Belgian coast, first Oostende and surroundings. The Imperial Navy were helped by pioneers of the army and fortification workers from Germany. Captured French and Belgian guns, also light navy guns and 15 cm guns were brought into position near the sea. The first defence nests were dug West and East of Oostende. On the roofs of hotels observation posts were installed.
Fore the following four years the coastal defence system was constantly improved and expanded. In order to nip a British landing in the bud, trenches, machinegun nests, and guns were placed in the dunes, supported by searchlights and guns for firing of light torches. At the beginning of 1915 already different 8,8 cm, 10,5 cm and 15 cm batteries had been built at Oostende and Zeebrugge.
Im Osten von Seebrügge wurde die Friedrichort Batterie mit vier kurzen 28 cm Geschützen aufgestellt Die Reichweite der alten Geschütze betrug nur 10 km. Eine andere, Batterie 'Groden', wurde im Westen von Seebrügge gebaut, ausgerüstet mit 28 cm Haubitzen, die jedoch gleichfalls nur 10 km weit schießen konnten. Die schweren Küstenbatterien wurden hinter der Dünenreihe und nahe den U-Boot-Basen gebaut. Sie mussten britische Schiffe, die versuchten, die Hafenanlagen mit Schiffsgeschützen zu zerstören, aus großer Entfernung unter Feuer nehmen. Die Batterien und die U-Boothäfen wurden darüber hinaus noch extra geschützt durch einen Gürtel von Luftabwehrgeschützen und Rauchschirmen.
to the east of Zeebrugge the Friedrichort Battery with 4 short 28 cm guns was installed. The range of the old guns was just 10 km. An other battery 'Groden' was built west of Zeebrugge, equipped with 28 cm howitzers, which also could only shoot as far as10 km. The heavy coast batteries were built behind the row of the dunes and near the submarine bases. They had to take under fire British ships that tried to destroy the port facilities with ship guns from a great distance. The batteries and the submarine ports were above that extra defended by a ring of anti-aircraft guns and smoke screens.
The first batteries were equipped with old-fashioned guns, or guns taken from ships that had been put out of commission. Newer 21 cm guns of the Hertha and Freya class had a far range (16 km). The Hindenburg battery at Oostende was then again equipped with obsolete guns. At first the guns were put up behind an earth parapet, later they were placed into a circular concrete bedding (Kesselbettung), and protected by armoured turrets. Many of the coast batteries were not only able to fire in direction of the sea , but could also take under fire targets on the land front at the Ijzer. Thus Nieuwpoort was taken under fire by the batteries Aachen, Cecilie and Beseler in 1915, the battery Antwerpen shot at Sint-Joris. The first modern battery Tirpitz (4 x 28 cm S.K.L/45) was ready in September 1915 and could fire projectiles over a distance of 30 km. Its fire was very accurate, as became obvious during an attack of British monitors on 7/9/1915. Different hits on the monitor Lord Clive were recorded. Captive balloons of the Marine Luftschiffer Abteilung and sea planes provided fire control and adaptation for the heavy batteries. Russian prisoners of war were forced to work building the heavy coast batteries, such as battery Deutschland at Bredene ( 4 x 38 cm) and Kaiser Wilhelm II at Knokke, which could take up the fight with British monitors which carried more and more heavy guns in order to put the port installations at Zeebrugge and Oostende out of work. During WW1 Oostende was shelled 45 times from the sea. During 1917 17cm batteries were built, among them Oldenburg, Preussen, Hessen and Braunschweig. Friedrichsort at Zeebrugge was also equipped with new 17 cm S.K.L/40 guns. Battery Deutschland was clear for action on 3/6/1917 with 3 heavy guns of 38 cm. In 1918 more than 220 guns (of 8.8 cm to 38 cm) were placed between Knokke and Lombardsijde. On 15th and 16th October 1918 German Marine-Artilleristen destroyed their guns and retreated. Only the railway guns could escape with them.
