The Allied invasion of Italy was the Allied amphibious landing on mainland Italy that took place from 3 September 1943, during the Italian campaign of World War II. The operation was undertaken by General Sir Harold Alexander's 15th Army Group (comprising General Mark W. Clark's American Fifth Army and General Bernard Montgomery's British Eighth Army) and followed the successful Allied Invasion of Sicily. The main invasion force landed around Salerno on 9 September on the western coast in Operation Avalanche, while two supporting operations took place in Calabria (Operation Baytown) and Taranto (Operation Slapstick).

The 10th Army (German: 10. Armee) was a World War II field army of Wehrmacht (Germany).

A new 10th Army was activated in 1943 as part of Adolf Hitler's last stand, who saw action notably in late 1943 and early 1944 along the "Winter Line" at the Battle of San Pietro Infine and the Battle of Monte Cassino, before finally surrendering near the Alps. Among its troops at Cassino were the XIV Panzer Corps and Parachute divisions of the Luftwaffe.