Passchendaele

Three traumatised German prisoners captured in an attack Photograph: Imperial War Museum

The allied advance begins. Lille suffers under British artillery fire Photograph: Imperial War Museum

British troops march towards trenches on the western front Photograph: Hulton-Deutsch Collection/Corbis

Friend and foe assist each other through the quagmire Photograph: Imperial War Museum

A German soldier leaves Flanders for the last time Photograph: Imperial War Museum

A stretcher-bearing party carrying a wounded soldier through the mud near Boesinghe during the battle of Passchendaele in Flanders Photograph: John Warwick Brooke/Getty

Soldiers of the 16th Canadian machine gun regiment using shell holes as makeshift defences at Passchendaele Ridge Photograph: William Rider-Rider/Getty

Final preparation of the Durhams: one GS shovel per four men Photograph: Imperial War Museum

A cemetery where troops killed in battle at Passchendaele are buried Photograph: General Photographic Agency/Getty

Queen Elizabeth II and the Duke of Edinburgh leave Waterloo station, London, for Belgium Photograph: Andrew Parsons/PA

A photo of first world war Australian soldier William Pegler, along with a poem and a poppy wreath which have been placed by family members, at the Menin Gate in Ieper, Belgium Photograph: Virginia Mayo/AP

Members of the British Royal Regiment of Fusiliers carry the coffin of an unknown private of the 2nd Battalion Lancashire Fusiliers over 90 years after he was killed in action during a reinterment at Tyne Cot Commonwealth war cemetery Photograph: Geert Vanden Wijngaert/AP

Queen Elizabeth II and Queen Paola of Belgium during a remembrance ceremony at Menenpoort Photograph: Dirk Waem/EPA

Honour guards stand on a monument at Tyne Cot cemetery Photograph: Virginia Mayo/AP