The Battle of the Somme lasted from 1 July 1916 to 18 November the same year. Following 18 months of trench deadlock in World War I, the battle was a joint operation between British and French forces hoping to achieve a final victory over the Germans on the Western Front.
A bombardment of over 1.5 million shells was fired at German lines in the seven days preceding the battle, with the aim of destroying enemy trench defences.
However, the Germans suffered less damage than expected from this tactic. This allowed German machine-gunners to confront the advancing British line, resulting in the deaths of 19,240 British soldiers on the first day. In the weeks that followed, there were over a million casualties from both sides. Here are some of the pictures from the conflict, followed by some of the most arresting images from World War I.