After the Battle of the Yser, which took place in October 1914, the artificial Yser inundations prevented a further German breaktrough. As a result, the conflict turned into a war of positions. While the German army took up post on the banks of the flooded Yser, the Belgians entrenched themselves behind the railway embankment between Nieuwpoort and Diksmuide. The belgian and German forces were separated by the flooded Yser and impenetrable swamps.
Petroleum tanks
To keep an eye on the enemy, soldiers captured church towers and factory chimneys. Near the Yser, the Germans set up two petroleum tanks as observation posts. The Belgian army tried to capture both tanks in May 1915, but failed. That is why the Belgians started to build a network of trenches towards the Petroleum Tanks, an extension straight to the German positions.