The Battle of Poelcappelle was fought in Flanders on 9 October 1917 by the British and German armies, during the First World War and marked the end of the string of highly successful British attacks in late September and early October 1917, during the Third Battle of Ypres. Only the supporting attack in the north achieved a substantial advance. On the main front the German defences withstood the limited amount of artillery fire managed by the British after the attack of 4 October. The ground along the main ridges had been severely damaged by shelling and rapidly deteriorated in the rains, which began again on 3 October, turning some areas into a swamp.