Top Photo: Adolf Hitler delivers a speech at the Kroll Opera House to the men of the Reichstag on the subject of Roosevelt and the war in the Pacific, declaring war on the United States. December 11, 1941. German Federal Archives Bild 183-1987-0703-507

On the morning of December 11, 1941, just four days after the devastating Japanese attack on the US naval base at Pearl Harbor, German Foreign Minister Joachim von Ribbentrop met with Leland B. Morris, the American chargé d’affaires at the US embassy in Berlin.

After outlining a series of American actions that Nazi leaders saw as hostile to their regime, Ribbentrop announced that his government “discontinues diplomatic relations with the United States of America and declares that under these circumstances brought about by President [Franklin D.] Roosevelt Germany too, as from today, considers herself as being in a state of war with the United States of America.”[1]

Later that afternoon, Adolf Hitler gave a dramatic speech to the Reichstag. Hitler charged that the United States and Roosevelt were under the control of “the eternal Jew” and had committed numerous “crimes” against Nazi Germany for years, from launching attacks on German and Italian ships at sea to secretly planning military attacks against Germany and the other Axis powers. Pointing to an alliance between Germany, Italy, and Japan known as the Tripartite Pact, Hitler vowed those nations would “together fight this war, a war that was forced on them by the United States of America and England, and bring it to a victorious end by deploying all instruments of power at their disposal.”[2]

Hitler’s announcement of war with the United States marked the end of years of careful maneuvering on the part of the Nazi leader to secure Germany’s objectives, while also avoiding war with America. On its face, the German declaration of war against the United States seems irrational; historian Martin Gilbert called it Hitler’s “single greatest mistake of the war.”[3] In recent decades, however, historians have explained Hitler’s decision as the logical result of his deeply held ideological beliefs and actions during the late 1930s and early 1940s. 

The Roots of Hitler’s Decision

Although Hitler never visited the United States, it occupied a great deal of his time and attention. Hitler’s first real encounter with Americans came during World War I when his unit engaged soldiers from the American Expeditionary Force (AEF) at the Second Battle of the Marne in summer 1918. The future dictator’s unit captured several American soldiers, including several German-American soldiers, who were able to communicate with their captors in their native language.[4]

After the war, Hitler wrote extensively about the United States in an unpublished sequel to Mein Kampf completed in 1928. Fearing that the United States would pose a serious economic threat to Germany’s future prosperity, Hitler wrote that his National Socialist Party “wishes to counter the union of the American states with a European one, in order to prevent the world hegemony of the North American continent.”[5] But while Hitler saw economic and political competition between the two countries as inevitable, he was realistic enough to recognize that it would take time for Germany to prepare for any military conflict with the United States.

After Germany invaded Poland in September 1939, President Roosevelt opted to maintain American neutrality. US policy was shaped by a series of laws known as the Neutrality Acts that limited a president’s ability to intervene in foreign conflicts. As long as these restrictions were in place, Hitler felt free to invade Western Europe without fear of American intervention. But he was also careful not to antagonize the Americans, lest they enter the conflict before Germany was ready to face them.

The Tripartite Pact

Saburo Kurusu, Adolf Hitler, and Galeazzo Ciano at the signing of the Axis Pact in Berlin on September 27, 1940. Imperial War Museum HU 75995
 

In the spring of 1940, German forces dramatically conquered much of Western Europe, overrunning and occupying Denmark, Norway, Belgium, the Netherlands, and France in less than six months. The fall of France in May 1940 and the evacuation of British and Allied forces from Dunkirk was an especially dramatic moment that shocked American officials on the other side of the Atlantic. While the United States remained officially neutral and even maintained diplomatic relations with the pro-Nazi Vichy regime in occupied France, American officials were deeply concerned that the war in Europe would inevitably involve the United States.

On September 27, 1940, German, Italian, and Japanese officials signed the Tripartite Pact, which committed the three powers to their shared purpose “to establish and maintain a new order of things calculated to promote mutual prosperity and welfare of the peoples concerned.”[6] In addition to their shared diplomatic and military concerns, Hitler also found deeper roots for an alliance with Japan in his belief that Japan’s rise to power in the Pacific owed much to German and “Aryan” influence.

Under the terms of the treaty, the three countries agreed to respect each other’s spheres of influence in Europe and Asia, and, under Article 3, to “assist one another with all political, economic, and military means when one of the three Contracting Parties is attacked by a power at present not involved in the European War or the Sino-Japanese Conflict.”[7] This clause of course included the United States.

Yet while this was an important diplomatic milestone in the history of World War II, it is important to note what the Tripartite Pact did not say: it did not require one signatory power to come to another’s aid in case of a preemptive attack. In other words, if one of the three signatory nations were to initiate a war with a country like the United States, the other two were not obligated to come to its aid under the treaty. These details would carry far-reaching consequences.

Operation Barbarossa

Hitler’s decision to invade the Soviet Union on June 22, 1941 was one of the most consequential decisions of the entire war. Dubbed Operation Barbarossa, German forces caught Soviet defenders by surprise and advanced rapidly into Soviet territory during the summer of 1941. Given the fact that the Soviet and Nazi regimes had signed a non-aggression pact in August 1939, the German invasion of the Soviet Union caught many observers by surprise. An attack on the Soviet Union by Germany’s Japanese allies could have helped the Germans in their war against Moscow, but the Japanese had already signed a non-aggression pact with the Soviets in April 1941.

After several months, Germany’s advance slowed as Soviet resistance stiffened and German casualties mounted. The Germans were also plagued by poor logistical support. They also had to contend with the fact that the Soviet Union started receiving significant military assistance from the United States as part of the Lend-Lease program, aid that totaled billions of dollars by the end of the war.

Facing a difficult campaign in the east and stubborn British forces in North Africa, Hitler came to believe that a Japanese attack on the United States in the Pacific would help Germany achieve its objectives. Less than two weeks before Japan’s attack on Pearl Harbor, Ribbentrop, the German foreign minister, met with Hiroshi Ōshima, Japan’s ambassador in Berlin, to discuss the two countries’ respective diplomatic and military situations. According to a German account of their conversation, Ribbentrop told the Japanese envoy that a showdown with the United States was inevitable. “One should not hesitate tackling the Americans right now,” Ribbentrop said, because “it seemed better at any rate to bring a problem to a head at the right moment than to keep on putting it off.”[8]

According to a Japanese account of the meeting that was later intercepted by the Americans, Ribbentrop went even further, telling Ōshima that “should Japan become engaged in a war against the United States, Germany, of course, would join the war immediately. There is absolutely no possibility of Germany’s entering into a separate peace with the United States under such circumstances. The Fuehrer is determined on that point.”[9]

With this statement, Hitler was going above and beyond the terms of the Tripartite Pact; in his eyes, the only way to give Germany a chance for success in a global war in which the United States was an active participant was for Germany’s ally—Japan—to distract the Americans with a war on the other side of the world. When the Japanese did so at Pearl Harbor, Hitler expressed surprise and relief: at a moment when the German Führer thought the Soviets were on the brink of collapse, he believed that the Japanese attack could not have come at a better time.[10]

Tense Days after Pearl Harbor

Germany waited until December 11, four days after the attack on Pearl Harbor, to declare war on the United States, and the Americans quickly responded in kind. But while the United States waited to declare war until after Germany did so first, that did not stop President Roosevelt from warning the American people about the dangers of Nazi Germany in the hours following the Pearl Harbor attack.

In a fireside chat delivered on December 9, 1941, the day after Congress declared war against Japan, Roosevelt charged that Japan’s path to war with the United States was more than just a parallel path to those of Nazi Germany and Fascist Italy. “It is actual collaboration,” he told the American people, “so well calculated that all the continents of the world, and all the oceans, are now considered by the Axis strategists as one gigantic battlefield.”[11]

Roosevelt’s December 8, 1941, speech calling for a declaration of war against Japan has become an iconic moment in American history. Yet the American declaration of war against Germany was a much more understated affair. After news of Germany’s decision reached Washington, Roosevelt sent a brief message to Congress asking for a declaration of war against Germany and Benito Mussolini’s Italy, which had also declared war against the United States. Although Roosevelt’s written message lacked the drama of a presidential address to a joint session of Congress, his words carried the full weight of this momentous decision. 

U.S. President Franklin D. Roosevelt as Senator Tom Connally stands by his side with a watch marking the exact time, signs the declaration of war against Germany, making the United States entry into Word War II in Europe on December 11, 1941. Library of Congress

Pointing to an unprecedented “challenge to life, liberty, and civilization,” the president warned that delay would only invite greater danger: “Rapid and united effort by all of the peoples of the world who are determined to remain free will insure a world victory of justice and of righteousness over the forces of savagery and of barbarism.”[12]

Both houses of Congress soon voted overwhelmingly in favor of declaring war against Germany and Italy, setting the stage for the United States to bring the full weight of its economic and military power to bear against the entire Axis alliance in the second global war of the 20th century.

For all the attention focused on the events of December 7-8, 1941, historians Brendan Simms and Charles Laderman argue that December 11 was the more important day, for, in their words, “It was Hitler’s declaration of war on the United States, much more than Pearl Harbor, that created a new global strategic reality and, ultimately a new world.”[13]

The Consequences of Germany’s Declaration

American entry into World War II had an immediate impact on the conflict. In addition to its ongoing campaigns in the Soviet Union and North Africa, Nazi Germany now faced the prospect of millions of American soldiers joining the conflict, along with millions of tons of military equipment and supplies flowing to the Allies. America's involvement in the war also had enormous consequences for international relations in second half of the 20th century: not only did US intervention mean that the world’s largest economy would now put its full economic and military might behind the Allies, it also set the United States on a path to becoming a global superpower in the postwar era.