Each player has air factors, which may be used either for "air superiority" (fighting the enemy air force), or to enhance the die roll for ground combat, to suppress ports or to interdict hexes, making them harder to move through; the numerically-superior air force, after winning the air superiority combat, may largely prevent the enemy from conducting the latter functions. Whereas the German Luftwaffe might have ten or twenty factors during the invasion of France in 1940, by 1944 the Western Allies alone might have approaching 100 air factors, enough to interdict almost every hex in France.