The Allied invasion of Italy began in early September, 1943. By early October '43, the southern 1/3 of Italy was in Allied hands. At that point the Allied advance became bogged down due to a variety of factors:
- They encountered a series of German defensive lines. Once one line fell, the Germans would retreat to the next. These lines took advantage of mountainous terrain.
- Hitler committed additional forces to stopping the Allied advance.
- Some Allied generals were overly timid; even to the point of disobeying orders.
- FDR opposed the commitment of D-Day-scale resources to the Italian campaign.
Despite the above, Rome fell in June of '44. Churchill had hoped that the Italian Campaign could be a springboard into Eastern Europe.
Churchill had hoped that a major advance in the autumn of 1944 would open the way for the Allied armies to advance north eastwards through the ‘Ljubljana Gap’ (the area between Venice and Vienna, modern Slovenia) to Vienna and Hungary to forestall the Russians advancing into Eastern Europe. Churchill’s proposal had been strongly opposed by the US Chiefs of Staff.
Stalin was also aware of postwar considerations. He strongly felt the Western democracies’ main advance should be in Northern France, not Italy.
Suppose FDR had sided with Churchill and against Stalin on this issue. No Normandy invasion, no landings in Southern France. Instead, an overwhelming commitment of invasion resources to Italy starting in ‘43. With such a massive commitment of resources, it’s likely Italy would have fallen much faster. This would not have been achieved by head-on attacks against prepared German mountain defenses. Instead, the Allies would have used a series of “peninsula hopping” operations; outflanking each successive German line by landing to the north. Had the Allies’ best general–Patton–been put in charge of these operations, and had they committed massive military resources, there is little doubt they would have succeeded.
Postwar Europe would have looked very different. There would have been a large-scale Western democratic presence in Central and even parts of Eastern Europe. Tens of millions of Europeans would have been spared the horror of Soviet occupation and Soviet rule.