First World War: The British Army detonated 19 ammonal mines under German lines, killing perhaps 10,000 in the deadliest non-nuclear man-made explosion in history during the Battle of Messines.

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. Major areas of conflict included Europe and the Middle East, as well as parts of Africa and the Asia-Pacific. The war saw 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 15 to 22 million military and civilian casualties and genocide. The movement of large numbers of people was a major factor in the deadly Spanish flu pandemic.