Would the U.S. Have Declared War on the Axis if Great Britain Fell in WWII due to a Nazi Invasion?

If Great Britain had fallen to a Nazi invasion during World War II, the reaction from the United States would likely have been complex and multifaceted, influenced by several factors including public opinion, strategic concerns, political response, and military preparedness. The hypothetical scenario of the Nazi victory over Britain would have had profound consequences for the course of the war and the future of democratic nations.

Public Opinion

Prior to the U.S. entering the war, there was significant isolationist sentiment among the American public. However, Britain's struggle against Nazi Germany had garnered considerable sympathy and support. If Britain had fallen, public opinion might have shifted dramatically, leading to increased calls for intervention in the war. The strong sentiment against Nazi Germany would have intensified, potentially altering the political landscape and accelerating the path to American involvement.

Strategic Concerns

The fall of Britain would have posed a significant threat to U.S. security. With the Atlantic coast potentially vulnerable to Nazi naval and air attacks, the U.S. would likely view the Axis powers as a direct threat. This strategic concern could have overridden isolationist tendencies and led to a more proactive approach in supporting the Allies. The U.S. would have seen it as a matter of national security to prevent the Axis powers from gaining a foothold in the Western Hemisphere.

Potential for Alliances

There was little chance that the U.S. would ally with the Axis powers. The ideological differences, particularly regarding democracy and totalitarianism, would have made such a partnership highly unlikely. Instead, the U.S. would probably have sought to build a coalition with any remaining Allied nations. This could have included countries like the Soviet Union, if it had not yet fallen under Nazi influence, or other nations resisting Axis control. The U.S. would have recognized that supporting the remaining Allies would be crucial in the fight against the Axis powers.

Political Response

President Franklin D. Roosevelt was already leaning toward supporting the Allies through measures like the Lend-Lease program. A Nazi victory in Britain could have galvanized the administration to formally declare war on the Axis powers. The perception that Nazi Germany was emboldened by its success in conquering Britain would have been a significant factor in the U.S. decision to intervene more decisively. The U.S. government would have felt a moral and strategic imperative to stand with Britain and other Allied nations.

Military Preparedness

By 1940, the U.S. was beginning to ramp up military preparedness. The fall of Britain would likely have accelerated this process and led to a more decisive military response against the Axis powers. The U.S. would have recognized the need to strengthen its defenses and prepare for a potential invasion. The growing military efforts would have included modernizing weaponry, increasing military spendings, and mobilizing the industrial capacity to produce war supplies.

In summary, if Great Britain had fallen to a Nazi invasion, it is highly likely that the U.S. would have declared war on the Axis powers, viewing the situation as a direct threat to its national security. The ideological and strategic significance of Britain's resistance would have made it difficult for the U.S. to ally with the Axis, and the weight of public opinion and strategic concerns would have driven a decisive shift in U.S. policy.