Complex sentence: The First Battle of Passchendaele took place on 12 October 1917 in the Ypres Salient of the Western Front, west of Passchendaele village, during the Third Battle of Ypres in the First World War.
Split into simpler sentences: The First Battle of Passchendaele took place on 12 October 1917, in the Ypres Salient of the Western Front, west of Passchendaele village. The attack was part of the Third Battle of Ypres in the First World War.