Horses carrying ammunition through knee-deep mud, Péronne in ruins, soldiers walking across the frozen Somme, Gordon Highlanders marching to the trenches – 100 years after the Battle of the Somme, photographers Matt Cardy and Peter MacDiarmid photographed sites scarred by the battle

Click here for the western front 1914-1916 and now

Click here for the key moments from the end of the war and its aftermath