Complex sentence: During World War II more than 100,000 belligerent troops, mainly Allied soldiers, were interned in Switzerland-internees from England, France, Poland and Russia, and Italians and Germans who fled combat.
Split into simpler sentences: During World War II more than 100,000 belligerent troops, mainly Allied soldiers, were interned in Switzerland. Internees from England, France, Poland and Russia, and Italians and Germans who fled combat.