Passchendaele epitomises everything that was most terrible about the Western Front. The photographs never sleep of this four-month battle, fought from July to November 1917, the worst year of the war: blackened tree stumps rising out of a field of mud, corpses of men and horses drowned in shell holes, terrified soldiers huddled in trenches awaiting the whistle.

This is a recently released book by Australian author Paul Ham.
A large book of 592 pages - should answer all questions about the battle....