W.I. Castle/Library and Archives Canada/via REUTERS
The first day of the battle was the worst single day in the history of the British Army's overall casualties with nearly 60,000 dead.
Despite appalling losses, the battle produced minimal gains for either side. The remainder of the battle quickly devolved into trench warfare, and upwards of 1,250,000 soldiers were killed or wounded before the battle ended on November 1, 1916.
Below, we have pulled archival images from the archives that show the terror of the battle.