Complex sentence: It remained in the area for the rest of the war and following the Italian surrender to the Allies in September 1943, the division was disarmed by the Germans and a large number of the men escaped to join the partisans.
Split into simpler sentences: It remained in the area for the rest of the war and, following the Italian surrender to the Allies in September 1943, the division was disarmed by the Germans. A large number of the men escaped to join the partisans.