World War I: In the Battle of Verdun, a German unit captures Fort Douaumont, keystone of the French defences, without a fight.

World War I or the First World War, also known as the Great War, was a global conflict between two coalitions: the Allies and the Central Powers. Main areas of conflict included Europe and the Middle East, as well as parts of Africa and the Asia-Pacific. There were important developments in weaponry including tanks, aircraft, artillery, machine guns, and chemical weapons. One of the deadliest conflicts in history, it resulted in an estimated 30 million military casualties, plus another 8 million civilian deaths from war-related causes and genocide. The movement of large numbers of people was a major factor in the deadly Spanish flu pandemic.

The Battle of Verdun was fought from 21 February to 18 December 1916 on the Western Front in France. The battle was the longest of the First World War and took place on the hills north of Verdun. The German 5th Army attacked the defences of the Fortified Region of Verdun and those of the French Second Army on the right (east) bank of the Meuse. Using the experience of the Second Battle of Champagne in 1915, the Germans planned to capture the Meuse Heights, an excellent defensive position, with good observation for artillery-fire on Verdun. The Germans hoped that the French would commit their strategic reserve to recapture the position and suffer catastrophic losses at little cost to the German infantry.

Fort Douaumont was the largest and highest fort on the ring of 19 large defensive works which had protected the city of Verdun, France, since the 1890s. By 1915, the French General Staff had concluded that even the best-protected forts of Verdun could not withstand bombardments from the German 420 mm Gamma guns. These new super-heavy howitzers had easily taken several large Belgian forts out of action in August 1914. Fort Douaumont and other Verdun forts were judged ineffective and had been partly disarmed and left virtually undefended since 1915. On 25 February 1916, Fort Douaumont was entered and occupied without a fight by a small German raiding party comprising only 19 officers and 79 men, entering via an open window by the moat. The easy fall of Fort Douaumont, only three days after the beginning of the Battle of Verdun, shocked the French Army. It set the stage for the rest of a battle which lasted nine months, at enormous human cost. Douaumont was finally recaptured by three infantry divisions of the Second Army, during the First Offensive Battle of Verdun on 24 October 1916. This event brought closure to the battle in 1916.