Winston Churchill instantly knew what Pearl Harbor meant for the British. He later wrote that when he heard the news that now that the United States was “in the war, up to the neck and in to the death” he felt the “greatest joy” because it meant that “we had won after all” and “England would live; Britain would live; the Commonwealth of Nations and the Empire would live”.

But while the benefits to Britain of the entry of the US into the war were clear, it is sometimes forgotten that Pearl Harbor also had an enormous impact on two other countries: Adolf Hitler’s Germany and Stalin’s Soviet Union.

The Japanese attack on Pearl Harbor affected the Soviet Union in two important ways. First, it confirmed that Japanese forces would no longer pose any foreseeable threat to the Soviet Union in the Far East. Indeed, reports two months earlier from Richard Sorge, the Soviet spy in Japan, that the Japanese intended to attack in the south rather than invade the Soviet Union, had informed Stalin’s decision to move divisions from the Siberian border to help in the defence of Moscow.

In early October 1941, Vasily Borisov was a soldier in a Siberian division in the remote east of the Soviet Union where, he says, “we were expecting Japan to attack”. But on 18 October his unit received orders to board trains immediately and head west to face a different foe: “In the summer [of 1941] we knew the Germans were advancing very fast and were capturing Soviet territory and we knew they were technically more advanced than us… we knew that the situation was bad”. As they travelled towards the west, Borisov and his comrades thought “that a lot of us would be killed. We knew that the war would be hard, and that’s what it turned out to be. It was very hard… we felt fear”.

But in the freezing Soviet winter, all the Germans’ technological advances counted for nothing. This was a more straightforward struggle – one in which the Red Army could compete on equal terms. And once Red Army soldiers began to counterattack against the Germans outside Moscow on 5 December, they became more and more confident. “We are very strong and very fit,” said Vasily Borisov. “This is Siberian spirit. This is how people are raised from childhood. Everyone knows that Siberians are very tough… I am a true Siberian, everyone knows that we are tough”. Vasily Borisov believed that he and his comrades held firm during the battle for Moscow because of this “Siberian stubbornness… The commanders used to say that the Siberian divisions saved Moscow…”

The second reason that Pearl Harbor had an instant effect on Stalin, and increased the chances of the Red Army winning against the German Wehrmacht, was because it led almost immediately to Germany declaring war on America, and so brought Stalin an unexpected ally of colossal potential power.

More like this

Hitler’s decision to declare war on America, announced on 11 December 1941, has often puzzled people who are not aware of the details of the history. Why, as German forces faced the immensity of the challenge of the war on the eastern front, did Hitler voluntarily add such a powerful additional enemy to his list of adversaries?

Hitler declares war on America, 11 December 1941. (Photo by Keystone-France/Gamma-Keystone via Getty Images)
Hitler declares war on America, 11 December 1941. (Photo by Keystone-France/Gamma-Keystone via Getty Images)

Why did Hitler declare war on America on 11 December 1941?

The answer is straightforward. Hitler, like Stalin, was a political leader who had an eye for reality, not just rhetoric. And to Hitler it had been obvious that war with the United States was inevitable. The key moment on that road to war had occurred not at Pearl Harbor but several months before, when President Franklin D Roosevelt had ordered American warships to accompany British convoys to the middle of the Atlantic. As Winston Churchill noted, by the time of the Atlantic Conference in August 1941, Roosevelt was determined “to wage war, but not declare it”. This was also the conclusion the German Grand Admiral Raeder had reached, and he had told Hitler months prior to Pearl Harbor that unless U-boats were allowed to sink American ships, the battle of the Atlantic could not be won.

Inevitably, following Roosevelt’s decision to order American warships to patrol the western Atlantic in support of convoys, a series of incidents followed – notably a U-boat attack on the USS Greer in September and the sinking of the USS Reuben James, causing the deaths of more than 100 American sailors, on 31 October 1941.

So, by December 1941, Hitler must have felt that by declaring war on America he was doing little more than accepting the inevitable – with the added benefit of retaining apparent control of events. Hitler further reasoned that the immediate entry of the US into the war would do nothing substantively for at least a year to alter the course of the struggle in the Soviet Union – and it was this fight against Stalin that he believed would decide the entire conflict one way or the other. Moreover, he thought the Japanese would now tie down the American fleet in the Pacific and threaten British interests in the Far East.

Hitler also drew another devastating conclusion from the entry of America into the war. For Hitler this was proof that “international Jewry” had orchestrated a world conflict, and in a radio broadcast to the German people immediately after the declaration of war he explicitly stated that “the Jews” were manipulating President Roosevelt just as they were his other great enemy, Joseph Stalin.

Hitler went still further in a speech he gave to the Nazi leadership, both Gauleiters and Reichleiters, the following day. He now linked the outbreak of this “world war” with his prophecy uttered in the Reichstag on 30 January 1939 in which he had threatened that “if the Jews succeed in causing world war” the result would be the “extermination of the Jews of Europe”. On 13 December, Nazi Propaganda Minister Joseph Goebbels wrote in his diary: “As far as the Jewish question is concerned, the Führer is determined to make a clean sweep. He prophesied to the Jews that if they once again brought about a world war they would experience their own extermination. This was not an empty phrase. The world war is here, the extermination of the Jews must be the necessary consequence. This question must be seen without sentimentality.”

Joseph Goebbels. (Photo by Keystone-France/Gamma-Keystone via Getty Images)
Joseph Goebbels. (Photo by Keystone-France/Gamma-Keystone via Getty Images)

Further proof that the air was thick with talk of “extermination” that week is provided by a speech that Hans Frank, ruler of a part of Poland the Nazis called the “General Government”, made to senior Nazi officials in Krakow on 16 December: “As an old National Socialist, I must state that if the Jewish clan were to survive the war in Europe, while we sacrificed our best blood in the defence of Europe, then this war would only represent a partial success. With respect to the Jews, therefore, I will only operate on the assumption that they will disappear… We must exterminate the Jews wherever we find them”. Frank, who had been one of those briefed by Hitler on 12 December, also added that “in Berlin” he had been told that he, and people like him, should “liquidate the Jews… themselves”.

The events of Pearl Harbor and the subsequent decision by Hitler to declare war on Germany did not ‘cause’ the Holocaust. Many Jews had already died before this date – Nazi killing squads, for instance, had been murdering Jews behind the lines on the eastern front since the start of the German invasion in June 1941. But what happened at Pearl Harbor and immediately afterwards brought a murderous clarity to Hitler’s thinking. And it was surely no coincidence that the year of the greatest killing in the Holocaust – 1942 – was just about to begin.

Much of the content of this article is taken from two books written by Laurence Rees: Auschwitz, the Nazis and the ‘Final Solution’ (BBC books, 2005) and World War Two – Behind Closed Doors (BBC books 2008). Rees is also the author of The Holocaust: A New History (Viking/Penguin, 2017)