PasschendaelePasschendaele 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 warblackened 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. The intervening century, the most violent in human history, has not disarmed these pictures