On the first day of the Battle of the Somme, 19,240 British soldiers were killed.
The date was July 1, 1916, when British and French forces launched a major offensive against the German Second Army in northern France. The British suffered 57,470 casualties that day in total, including the dead, wounded, missing and prisoners. The death toll of 19,240 made it the bloodiest single day in the history of the British Army.
The attack followed a week-long artillery bombardment intended to destroy German defenses. In several southern sectors, British and French troops made progress, but attacks farther north encountered intact wire, machine guns and fortified positions. Many soldiers crossed open ground carrying heavy equipment and were exposed to concentrated fire.
The 19,240 figure refers specifically to British deaths, not total British casualties. It also excludes French and German losses. The catastrophe helped expose the limits of pre-battle bombardment and became a defining symbol of the industrialized attritional warfare of World War I.