My nod goes to Kesselring, whose contribution is much underrated. For almost two years he kept the Allied forces in Sicily and Italy at bay with minimal numbers of troops and his forces did not finally surrender until the Soviets were attacking Berlin. Anyone who wishes to learn defensive strategy and tactics would do well to study his conduct of that campaign.
This times a billion. He also had to contend with partisan activity that, while not nearly as extensive in scale as on the Eastern Front, was certainly nothing to sneer at.