In 1917, British forces planned to seize the railway running behind the German lines in an attempt to advance on the German submarine base at Bruges. At this time of the conflict, the German U-boat campaign had become even more intense and was threatening Britain with defeat.
This major British offensive heralded the beginning of the Third Battle of Ypres. As part of the attack plan, 19 mines were detonated under the German lines at Messines Ridge, causing explosions which could be heard as far away as London (Battle of Messines).
Yet, waterlogged conditions, caused by frequent periods of rain, and the strongly fortified German defence lines enclosing the Ypres Salient made an Allied advance impossible.
The following ‘Battle of Passchendaele’, which ended with the capture of Passchendaele village, merely widened the Ypres Salient by 8 kilometres and resulted in 400,000 killed, wounded and missing soldiers on the British side alone.
For the first time, during the Third Battle of Ypres, German troops made use of mustard gas as opposed to chlorine gas in the Second Battle of Ypres. It was also named ‘Yperite’ after the city of Ypres where it was used for the first time. It blistered the skin, eyes and lungs, and killed thousands of soldiers in a most painful and often slow way.
The tragedy for the Allied armies, who suffered so many losses, was that only a few months later almost all of the ground won in the Third Battle of Ypres was regained by the Germans during the Spring Offensive in 1918.