From 31 July to 10 November the Third Battle of Ypres included the First Battle of Passchendaele and culminated in the Second Battle of Passchendaele. The battle had the original aim of capturing the ridges east of Ypres then advancing to Roulers and Thourout to close the main rail line supplying the German garrisons on the Western front north of Ypres. If successful the northern armies were then to capture the German submarine bases on the Belgian coast. It was later restricted to advancing the British Army onto the ridges around Ypres, as the unusually wet weather slowed British progress. The Canadian Corps relieved the II ANZAC Corps and took the village of Passchendaele on 6 November, despite rain, mud and many casualties. The offensive was costly in manpower for both sides for relatively little gain of ground against determined German resistance but the ground captured was of great tactical importance. In the drier periods, the British advance was inexorable and during the unusually wet August and in the Autumn rains that began in early October, the Germans achieved only costly defensive successes, which led the German commanders in early October to begin preparations for a general retreat. Both sides lost a combined total of over a half million men during this offensive. The battle has become a byword among some British revisionist historians for bloody and futile slaughter, whilst the Germans called Passchendaele "the greatest martyrdom of the war."