Tobruk was the site of an ancient Greek colony and, later, of a Roman fortress guarding the frontier of Cyrenaica. Over the centuries, Tobruk also served as a waystation along the coastal caravan route. By 1911, Tobruk had become an Italian military post, but during World War II, Allied forces, mainly the Australian 6th Division, took Tobruk on 22 January 1941. The Australian 9th Division ("The Rats of Tobruk") pulled back to Tobruk to avoid encirclement after actions at Er Regima and Mechili and reached Tobruk on 9 April 1941 where prolonged fighting against German and Italian forces followed.