第一次世界大战期间,德国人未能击败法国,并把法国的盟友英国逐出欧洲大陆,因此当1917年美国人参战时,他们就能够增援西欧战场。第二次世界大战的情况则截然不同。法国政府的垮台并于1940年从敦刻尔克撤退,意味着英美不得不依靠水陆两栖进攻,在西欧重新开辟一个战场,然后他们才能与德国部队的主力进行 During the First World War, the Germans failed to defeat France and expelled the French ally Britain from the European continent. When the Americans entered the war in 1917, they were able to reinforce the Western European battlefield. The situation in World War II was completely different. The collapse of the French government and its withdrawal from Dunkirk in 1940 meant that Britain and the United States had to rely on the amphibious offensive to reopen a battlefield in Western Europe before they could engage with the main forces of German troops.