 The Battle of Messines in June and the Battle of Pilckem Ridge which began on 31 July had captured ground but left the Germans in possession of the most important positions on the Gheluvelt Plateau.Torrential rain in August interrupted the tempo of the British advance and at the Battle of Langemarck the Germans lost ground in the north but again held most of the ground on the Plateau.In view of the failure of the Fifth Army to make much headway in August, Haig decided to transfer more offensive weight towards the south-east, along the southern half of Passchendaele Ridge.