World War I: Battle of Messines: Allied soldiers detonate a series of mines underneath German trenches at Messines Ridge, killing 10,000 German troops.

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 Messines was an attack by the British Second Army, on the Western Front, near the village of Messines in West Flanders, Belgium, during the First World War. The Nivelle Offensive in April and May had failed to achieve its more grandiose aims, had led to the demoralisation of French troops and confounded the Anglo-French strategy for 1917. The attack forced the Germans to move reserves to Flanders from the Arras and Aisne fronts, relieving pressure on the French.

Several underground explosive charges were fired during the First World War at the start of the Battle of Messines (7–14 June 1917). The battle was fought by the British Second Army and the German 4th Army near Mesen in Belgian West Flanders. The mines, secretly planted and maintained by tunnelling companies of the Royal Engineers beneath the German front position, killed many German soldiers and created 19 large craters.