The Battle of Leros was the central event of the Dodecanese campaign of the Second World War, and is widely used as an alternative name for the whole campaign. After the Armistice of Cassibile the Italian garrison on the Greek island Leros was strengthened by British forces on 15 September 1943. The battle began with German air attacks on 26 September, continued with the landings on 12 November, and ended with the capitulation of the Allied forces four days later.

Leros, also called Lero, is a Greek island and municipality in the Dodecanese in the southern Aegean Sea. It lies 317 kilometres from Athens's port of Piraeus, from which it can be reached by a nine-hour ferry ride or by a 45-minute flight from Athens. It is about 32 kilometres (20 mi) from Turkey. Leros is part of the Kalymnos regional unit. It has a population of 7,992 (2021).