The process Allied invasion of Italy, was the Allied invasion of mainland Italy in September 1943, by General Harold Alexander's 15th Army Group (comprising Mark Clark's U.S. Fifth Army and Bernard Montgomery's British Eighth Army) during World War II. The operation followed the successful invasion of Sicily during the Italian Campaign. The main invasion force landed around Salerno on the western coast in Operation Avalanche, while two supporting operations took place in Calabria (Operation Baytown) and Taranto (Operation Slapstick).