The German declaration of war against the United States on Dec. 11, 1941, four days after the Japanese attack on Pearl Harbor, on Dec. 7, 1941, was a turning point in the history of World War II, and thus in the history of international relations. 

The Japanese attack, which caught the United States by surprise, led to the death of 2,403 people and to a declaration of war by the United States against Japan. The subsequent declaration of war by Germany against the United States introduced the latter into the European theatre, alongside Britain and the Soviet Union. It thus transformed the war in Europe. 

Why would Adolf Hitler declare war on the United States when Germany was dealing with a major challenge on its eastern front in the war against the Soviet Union? Why would Germany, on its own initiative, enlarge the war in Europe in such a way as to render it considerably more difficult to win it? 

Certainly, Germany had seen the United States not as a neutral power, but rather as pro-British. As far as Germany was concerned, the declaration of war might actually afford it more leeway, more freedom of maneuver to deal with the perceived danger of U.S. military assistance to Britain. Further, Germany asserted that its declaration of war was prompted by its commitment to Japan that it would come to its aid in case of war. However, Germany had promised that it would come to the aid of Japan in case the latter was attacked, which clearly was not the case.  

Whatever the reasons that prompted the German declaration of war against the United States, the result was a significant change for the worse for Germany, and a considerable sigh of relief for Britain and the Soviet Union. No matter how much President Franklin Roosevelt wanted to help Britain in the war, he had to deal with a Congress and public opinion wary of foreign entanglements. The Japanese attack, and the subsequent German declaration of war, rallied the country behind the president in fighting a war, which now seemed to be inevitable. The entry of the United States in the war was a turning point as it introduced the most powerful industrial country on earth on the side of Britain and the Soviet Union. Without having to resort too much to counterfactual history, there is little doubt that without the United States, the European war would have developed differently. Britain and the Soviet Union might have won the war, after all, but the price would have been considerably higher and it would have taken significantly more time. Without the United States, the European war might have finished in a stalemate, without a clear winner. What is clear is that the German declaration of war against the United States altered German fortunes considerably for the worse. 

To be sure, the United States had been assisting Britain prior to the German declaration of war. However, there was a major difference between assisting Britain and intervening directly on the side of Britain. The full might of the United States was to be deployed against Germany, altering the nature of the war in Europe. Hitler might have thought that by declaring war on the United States he would divide the latter’s attention and power between two war theatres and thus weaken it. However, the declaration of war against the United States also led to the weakening of Germany, which had to confront not only the Soviet Union and Britain but also the United States. Hitler apparently believed that, sooner or later, Germany would have had to fight the United States, so maybe it was better to take the initiative and do so sooner when the United States was perhaps not yet prepared for the challenge. 

The Japanese attack on the United States enlarged the war significantly by introducing the full might of the latter to the war in the Far East. The declaration of war by Germany against the United States was to the western front in Europe what the German invasion of the Soviet Union was to the eastern front. By its own volition, Germany introduced into the war the two potentially most powerful enemies: the Soviet Union, by launching a surprise attack against it, in June 1941 and the United States, by declaring war against it in the wake of the Japanese attack in Pearl Harbor, in December 1941. 

Both actions undertaken by Germany were to become watersheds. However, if Germany might have been able to withstand a war against Britain and the Soviet Union, then the entry of the United States would tilt the balance significantly to the detriment of Germany and its allies. With the benefit of hindsight, the declaration of war by Germany against the United States could be said to have been, in the long run, a crucial turning point as it would render the German war effort in Europe considerably more difficult, if not altogether impossible. In this context, it’s interesting to note that the two surprise attacks, by Germany against the Soviet Union, and by Japan against the United States, represented a singularly traumatic experience for the Soviet Union and the United States, respectively, from which both were able to come out ultimately victorious, albeit after a long and bloody war.    

For a country veering between isolation by Congress and intervention by the White House, the dilemma of whether to help Britain or not and to what extent, came to a definite end by the Japanese attack on Pearl Harbor and the German declaration of war. The latter was either an act of loyalty or folly. Either Germany wished to display its unflinching support to its Japanese ally, even when it was not obliged to do so, or it sought to demonstrate its self-confidence, following a series of rapid victories in Europe. Nazi Germany had no sense of limits. That led it to invade the Soviet Union and to declare war on the United States, an action that would become a significantly important turning point in the way World War II would evolve. 

Dr. Yoav J. Tenembaum is a lecturer in International Relations at Tel Aviv University, Israel. 

Image: Reuters