Croatian soldier fighting with the Germans under the banner of the Croatian Division. He carries a M-36 machine gun and plenty of spare ammunition. Note the "potato masher" grenade stuck under his belt.
Friday 1 July 2016 marks the centenary of the beginning of the Battle of the Somme, the biggest conflict seen on the Western Front during World War I. Here are some of the most arresting photos from the war. Contains graphic images.