Allied invasion of Italy of historian Carlo D'Este, Clark "mistakenly believed he had saved the Allied invasion by his leadership, when in fact it was precisely his inexperience that precipitated most of the problems the invasion force faced." Allied invasion of Italy The Allied invasion of Italy was the Allied amphibious landing on mainland Italy that took place on 3 September 1943 during the early stages of 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 Fifth Army and General Bernard Montgomery's British Eighth Army) and followed the successful
Operation Avalanche tie down German forces, keeping them away from the planned invasion of Normandy – Operation Overlord. However, General George Marshall and much of the American staff wanted to undertake no operations that might delay the Normandy invasion. When it became clear that Operation Overlord could not be undertaken in 1943, it was agreed forces in North Africa should be used to invade Sicily, with no commitment made to any follow-up operations. Joint Allied Forces Headquarters AFHQ were operationally responsible for all Allied land forces in the Mediterranean theatre and it was they who planned and commanded the invasion of Sicily