World War I: The last Australian troops are evacuated from Gallipoli.

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 Gallipoli campaign, the Dardanelles campaign, the Defence of Gallipoli or the Battle of Gallipoli was a military campaign in the First World War on the Gallipoli Peninsula from 19 February 1915 to 9 January 1916. The Entente powers, Britain, France and the Russian Empire, sought to weaken the Ottoman Empire, one of the Central Powers, by taking control of the Turkish straits. This would expose the Ottoman capital at Constantinople to bombardment by Entente battleships and cut it off from the Asian part of the empire. With the Ottoman Empire defeated, the Suez Canal would be safe and the Bosphorus and Dardanelles straits would be open to Entente supplies to the Black Sea and warm-water ports in Russia.