Western Allies started a strong offensive, aimed at taking Rome, in the first turn of February 1944 (turn 82). They enjoyed fair weather and good air support so in a matter of 3-4 turns, all Gustav Line forts were destroyed. As soon as April 27, 1944 (turn 86) Allies entered Rome. Only a couple of Wehrmacht mountain units escaped destruction and withdrew to northern Italy:

Requirements for other fronts kept this scenario from being reinforced by the Germans so as soon as 3 turns later June 26, 1944, Allies were already in Florence. By late Summer all northern Italy were conquered by the Allies, Allied forces coming from central Italy being helped by others coming from southern France, place in which Allies had landed in April 7, 1944.
In 5 October, 1944 (turn 94), the entire Italian peninsula was in Allied hands, Allies even linking with Yugoslavian partisans.