Bulgaria signs the Armistice of Salonica ending its participation in World War I.

The Armistice of Salonica was the armistice signed at 10:50 p.m. on 29 September 1918 between Bulgaria and the Allied Powers at the General Headquarters of the Allied Army of the Orient in Thessaloniki. The armistice came into force at noon on 30 September 1918. The armistice would remain in effect until the conclusion of the Treaty of Neuilly-sur-Seine, the final general peace treaty, in November 1919.

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.

September 29 is the 272nd day of the year in the Gregorian calendar; 93 days remain until the end of the year.