Early December 1941 was a momentous point when two wars at opposite ends of the world – in Europe and in the Far East – became joined in one colossal global conflict. On 7 December, the Japanese bombed Pearl Harbor. Four days later, Hitler took Germany into war against the United States of America.


Hitler’s move seems one of the most puzzling decisions of the Second World War: to declare war on a country possessing immense economic and military might, with no weaponry or strategy in place to attack, let alone defeat, her, and precisely at the time of trying to fend off a dangerous counter-offensive by the Red Army in what, against early expectations, had become a bitter and protracted war in the Soviet Union.

What prompted Hitler to take a decision which seems so bizarre, so predictably self-destructive? Can it be put down simply to an expression of his rampant megalomania? Was it purely a reckless gamble with Germany’s existence as a nation, with no prospect of success, a sign of unbelievable strategic idiocy, a move of utter madness by a sick leader?

Speech of Adolf Hitler to the Reichstag inthe Kroll Opera in Berlin after the Declaration of war to the USA, in addition to the lectern to the right: Press Chief Otto Dietrich and the personal adjutant of Hitler Albert Bormann the Brigade Commander o
Adolf Hitler delivers a speech to the Reichstag in Berlin after declaring war on the USA. (Photo by Heinrich Hoffmann/ullstein bild via Getty Images)

In the early period of Nazi rule, America scarcely figured in the formulation of foreign policy. Hitler did not mention the USA when he laid out his strategic imperatives to his military commanders in November 1937. America remained largely an irrelevance to Hitler during 1938, as Germany swallowed up Austria, then the Sudetenland. But the outrage in the USA about the terrible pogroms in November that year sharpened the antagonism towards Germany, at the same time intensifying Hitler’s paranoia about the power of Jewish warmongers in America.

This was part of the background to Hitler’s notorious “prophecy” on 30 January 1939 that, in the event of another war caused, as he saw it, by Jewish finance, the Jews would be destroyed. That was followed by a ferocious verbal assault on US President Roosevelt by Hitler in a Reichstag speech three months later. By this time the Nazi leadership saw America as a potential future enemy, lined up on Britain’s side, in a war that was looming.

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Would America have declared war on Germany?

By declaring war on the USA on 11 December 1941, Hitler spared Roosevelt a tricky decision. Immediately following the Pearl Harbor attack, the President and his advisers deliberated whether to declare war on Germany, a move which would undoubtedly have faced serious opposition in Congress. They decided there was no need. They were reading Japanese intelligence signals and were aware of the agreement between Germany and Japan. They knew that a German declaration of war was imminent.

Even without the German move, however, full American involvement in the European war would have been likely in the near future. Confronting the threat from Germany had always been seen as the priority by the US administration. Escalation of the war in the Atlantic was inevitable.

Beyond this, the Victory Program was predicated upon sending a major land force to fight in Europe. The war could not, therefore, have been confined to the Pacific. Possibly Roosevelt could in the short term have avoided a formal declaration against Germany. But the intensification of the Atlantic War and American strategic plans meant that a US declaration could almost certainly not have been long delayed, even had Hitler not preempted it.

This meant thinking strategically, not just ideologically, about America. The key concern was to keep the USA out of the European conflict until Germany had won it. There was no immediate worry. A shift to belligerency, it was reckoned, could not take place before the US presidential election that was due in November 1940. And the prominent strain of isolationism in the country and in Congress posed an obstacle to intervention. This could in any case be militarily ruled out for the foreseeable future. In spring 1940, the US regular army ranked twentieth in the world, one place behind the Dutch army, and comprised only 245,000 men, with a mere five fully equipped divisions – Germany engaged 141 divisions in the western campaign alone. Even so, America was rearming fast. German prognoses were that it would be something like a year and a half before American military and economic potential could make itself felt. Hitler spoke of his confidence that he would have “solved all problems in Europe” long before the Americans could intervene. But “woe betide us if we’re not finished by then”, he had privately commented.

Hitler spoke of his confidence that he would have 'solved all problems in Europe' long before the Americans could intervene...

The thought lay behind the decision, taken in effect within a month after the stunning victory over France, to attack the Soviet Union. Though the underlying motivation was ideological, the urgency was strategic. Britain, against the odds, was still in the war. Forcing her into submission through an invasion was such a risky proposition that Hitler and the German navy were reluctant to undertake it.

Destroying the Soviet Union in a rapid campaign lasting only a few weeks seemed a better option. Britain would then be compelled to negotiate. And America, a growing danger as long as Britain remained in the war, would (such was the thinking) then keep to her own hemisphere. Germany would have won. On the other hand, the longer the war continued, with Britain undefeated, the more American might would tell, as it had done in 1917–18. “We must solve all continental European problems in 1941”, Hitler told his chief military adviser, General Alfred Jodl, in December 1940, “since from 1942 onwards the United States will be in a position to intervene”.

Hitler had cause to worry. The passing of the Lend-Lease bill by the US Congress in March 1941 gave the clearest indication that an undefeated Britain would, over time, be able to call upon immeasurable American resources to help the war effort. And in July 1941 US army planners began work on a “Victory Program”, which assumed that only American entry into the war could ensure Germany’s total military defeat, and envisaged sending a huge force of around five million men to fight in Europe. This army was to be ready by 1 July 1943.

By the time the German invasion of the Soviet Union began on 22 June 1941, Japan was playing a vital part in Hitler’s stategic thinking. During the euphoric early phase of the eastern campaign, when it looked as if victory was imminent, Hitler suggested to the Japanese Ambassador in Berlin, Oshima, that Germany and Japan should jointly destroy both the Soviet Union and the USA. He had already, in fact, briefly envisaged establishing bases on the Azores from where long-range bombers could attack the east coast of America. By mid-August 1941, however, it was plain that the swift knockout of the USSR had not succeeded. The war would drag on. And it was a matter of time before America entered it.

Hitler’s invincible ally

Hitler’s hopes now rested, therefore, in no small part on full-scale war between Japan and America. This would, he imagined, keep the USA fully engaged in the Pacific, diverting them from the Atlantic and the war in Europe, and leave Germany time to finish off the Soviet Union. Hitler had already indicated the previous April, in fact, that “Germany would promptly take part in the event of a conflict between Japan and America, for the strength of the allies in the Tripartite Pact (signed the previous September by Japan, Germany and Italy) lay in their acting in common. Their weakness would be in allowing themselves to be defeated separately”. The comment hints at Hitler’s reasons for declaring war on the USA in December.

Meanwhile, US President Roosevelt was determined to exploit Hitler’s “diversion” in the east and gradually stepped up what he referred to as an “undeclared war” in the Atlantic. In the autumn, the number of incidents involving American shipping and German U-boats increased. In September, Roosevelt adroitly embellished one such incident to justify the escorting of convoys by American warships and a “shoot on sight” policy against German submarines. The head of the German navy, Grand Admiral Raeder, was champing at the bit to retaliate. But Hitler, as he had done all summer, held him back. The German dictator fumed, but felt his hands tied in the Atlantic.

Franklin Delano Roosevelt Holding Resolutions
President Roosevelt holds the resolutions that put the United States at War with Italy and Germany (Getty Images)

He desperately wanted Japan to open up hostilities in the Pacific. When the outrightly hawkish General Tojo became the prime minister of Japan in mid-October 1941, German hopes were raised. On 5 November the Japanese made a tentative enquiry about “a German assurance not to conclude a separate peace or armistice in case of a Japanese-American war”. Hitler’s Foreign Minister Ribbentrop quickly agreed that in the event of war between Japan or Germany and the USA, any armistice would only be concluded jointly. He was happy to have this made into a formal agreement. The Japanese now sought precisely such a binding commitment that Germany would offer military support in a war against the USA, even if Japan started it – a contingency not covered by the Tripartite Pact.

Hitler was ecstatic at the news of Pearl Harbor. He spoke of the Japanese attack as 'a deliverance'...

By the end of November, as the Japanese decision to go to war against the USA was being taken, Ribbentrop provided the assurance that Germany would join the war immediately, and that there would be no separate peace under any circumstances. “The Führer is determined on that point”, he declared. The drafting of the new agreement went ahead. But it was still not signed when Japanese planes attacked Pearl Harbor.

Hitler was ecstatic at the news of Pearl Harbor. He spoke of the Japanese attack as “a deliverance”. “We can’t lose the war at all”, he exclaimed. “We now have an ally which has never been conquered in 3,000 years”. Those around him swiftly drew the conclusion that Germany would now declare war on the USA. In fact, it took a few days to assemble the Reichstag and make the necessary preparations. But significantly, without waiting for a formal declaration, Hitler removed the shackles from his U-boats and gave them free licence to attack American shipping. He told Ribbentrop two days before the declaration that the main reason for Germany opening up warfare against the USA was “that the United States is already shooting against our ships. They have been a forceful factor in this war, and they have, through their actions, already created a situation which is practically, let’s say, of war”.

Why didn’t Japan declare war on Russia?

For six weeks in summer 1941, Japanese leaders assessed the merits of attacking the Soviet Union. Attractive though the option appeared to some factions, it was revealed on closer examination to be extremely risky.

A key factor was Japan’s significant military inferiority on the Soviet border. Opponents argued that a reduction of about half of Soviet ground forces and two-thirds of the air-force in the Far East would be needed for a Japanese attack to be contemplated. (The memory of the 1939 war on the Mongolian border, when 17,000 Japanese troops had been killed or injured no doubt played its part in the caution.) Japanese forces for an attack on the Soviet Union could in any case not be ready before late August. And operations would have to be completed by mid-October, when the Siberian winter set in. The timetable was extremely tight.

Beyond this, the Japanese were less confident than Hitler that Germany would swiftly defeat the Soviet Union. So a policy of wait-and-see was adopted towards the northern plan. An advance to the south, to which the Japanese were already committed, still seemed a more attractive proposition. The most likely outcome to an attack on the Soviet Union would have been defeat for Japan, not victory for the Axis powers. It would, however, have altered the overall course of the war. In such an event, a weakened Japan would probably have been forced to back away from the southern advance and certain confrontation with the USA.

On 11 December, just before Hitler’s speech to the Reichstag, the new, important agreement with Japan was signed. The key clause ruled out an armistice with the USA or Britain without mutual consent. Hitler now had a formal agreement with an ally which he thought invincible. America, such was his thinking, would be held down in the Pacific. Moreover, with German entry, she would be faced with a two-front war. The necessary spread of US resources, however formidable, would give Germany the opportunity to win the war in Europe before America could make a difference there.

But, above all, Japanese entry gave Germany the chance to turn the tables in the Atlantic. “Our U-boat commanders had reached the point where they didn’t know any longer whether or not they should fire their torpedoes”, he told Nazi Party leaders on the day after the declaration.

“A U‑boat war can’t be won in the long run if the U-boats are not free to fire”. For Hitler, as these remarks make clear, the one-sided state of “undeclared war” with America was the main reason for his decision. He now had the opportunity and justification for opening up all-out submarine warfare in the Atlantic, something he had been itching to do all summer and autumn. It was his only way of attacking America. And without forcing the USA onto the retreat, possibly to concessions, and breaking the convoy supplies to Britain, the war could not be ended. Pearl Harbor provided the occasion. And the newly-reached agreement with Japan which ruled out a separate peace offered the safeguard he needed.

One other factor in the decision was of importance: prestige. “A great power doesn’t let itself have war declared on it, it declares war itself”, Ribbentrop remarked – doubtless echoing Hitler. It was certain in Hitler’s mind that war with the USA could not be avoided for much longer. Propaganda considerations demanded that the decision be in German, not American, hands. Whether, in fact, Roosevelt would have been bold enough to seek from Congress a declaration of war against Germany as well as Japan is questionable. As it was, Hitler took the quandary away from the American president.

The decision was no puzzle. But it was madness all the same...

So was it a puzzle? From Hitler’s perspective, it was only preempting the inevitable. It was consistent with his longstanding view that the USA would always stand in Germany’s way. It matched his strong fear that time was against Germany. It accorded with his instincts for prestige and propaganda. It was taken at a euphoric moment when “the Asian conflict drops like a present into our lap”, as Goebbels put it. Above all, it had an internal rationale: make sure that Japan stays in the war to hold down the Americans in the Pacific, weaken the British in the Far East, force the USA into a two-ocean war, and use the U-boats to turn the tables on Roosevelt in the Atlantic, severing supplies to Britain and allowing Germany the time to defeat the Soviets in the east or at least force them to a peace on German terms.

The decision was, therefore, no puzzle. But it was madness all the same – part of the madness behind the entire German gamble for world power.

Sir Ian Kershaw is professor of Modern History at Sheffield University, and one of the world’s leading authorities on Hitler

This article was first published in the June 2007 issue of BBC History Magazine

Hitler’s other key decisions

Why did Hitler attack the Soviet Union?

Hitler had, of course, since the 1920s envisaged war against the Soviet Union to acquire “living-space” for Germany and destroy “Jewish-Bolshevism”. These underlying ideological motives were undiminished in 1940. But the concrete plan to attack the USSR without delay, in June 1941, was driven by strategic considerations. Despite France’s defeat, Britain refused to contemplate a negotiated end to the war. And behind Britain loomed the spectre of America. Hitler knew that time was not on Germany’s side. He had to end the war quickly. British hopes, in his view, rested on the Soviet Union. Unless he acted, he claimed, the USSR could stir up trouble in the Balkans or even, incited by Britain, attack Germany. The way to force Britain to the conference table, he asserted, was to crush the Soviet Union in a rapid assault. America would then keep out of the European war. Victory would be Germany’s.


Why did he instigate the Holocaust?

Hitler had declared in January 1939 that in the event of another world war the Jews would be destroyed. How this would come about was unclear. But there was an awful, inexorable logic to the emergence of full-scale genocide in 1941 even if the actual steps that year which culminated in the “Final Solution” followed no clear blueprint. Hitler’s role in this process, though shadowy, was indispensable. The killing of Soviet Jews which began with the invasion of the USSR in June was by August extended to include women and children. But the planned deportation of millions of non-Soviet Jews into the USSR soon became impossible because the war could not be ended. With Hitler’s decision in September to deport the Reich Jews “to the east” acute pressures nevertheless built up to find a “solution”. By the end of the year, Poland was emerging as the location and gassing as the method.