Italy's departure from the Axis could create a new front against Germany, especially if Italy then joined the Allied coalition. Allied troops could land in Italian-controlled French territory and advance north to liberate France. That route would avoid beginning with an assault on German-held coastal defences. The timing matters because Germany had not yet built the Atlantic Wall, while an earlier Italian collapse could also change whether Germany intervened in Greece.
Notable Point · 2:46:44-2:47:53
An Italian change of sides could open a route into France
If Italy joined the Allies, its occupied French territory could provide a landing area for an advance before the Atlantic Wall existed.