Did Hitler know about the Pearl Harbour attack in advance?

The attack on Pearl Harbour was always going to bring the US into the war. In fact Hitler declared war on the US just four days later. But bringing another enemy into the war must surely have been bad news for Germany. How much did Hitler know about the attack on Pearl Harbour beforehand? Did he know the plans, did he help with the planning? Based on a timeline of events it seems that he did know hostilities between the US and Japan were imminent but didn’t know details of the attack itself.

When the Japanese attacked Pearl Harbour in December 1941 it ushered in a new phase of the second world war. The US would be forced to enter the war and with their vast resources and expertise it would be changed forever. That much would have been obvious to any observer on either side before the attack.

But, how much did Hitler know about the attack beforehand. The answer, it seems, is none of the details. However, when you look at the timeline of events it seems clear that Germany were aware that hostilities were going to take place and very soon.

Germany, Japan and Italy had formed the Tripartite Pact in September 1940. This meant that if either of the countries were attacked the others would come to their aid. Crucially it didn’t bind the parties if one of the countries initiated the attack themselves. If the US had attacked Japan then Germany would come to their aid. But the other way around, if Japan attacked first, then Germany was under no obligation.

Of course what Hitler really wanted was for Japan to attack Russia. The campaign in Russia, Operation Barbarossa [URL], had stalled and was proving to be harder than anticipated. An attack by Japan on Russia would greatly help out the German campaign and in fact had been urged by Hitler in a statement to Ambassador Oshima in June 1941.

It would, of course, be up to Japan to act as it saw fit, but Japan’s cooperation in the fight against the Soviet Union would be welcomed if the [Japanese] advance to the south should run into difficulty because of supply and equipment.

— Adolf Hitler to Ambassador Oshima (2 June 1941) [Source: Jäckel, Eberhard: Hitler in History]

If Japan wasn’t going to attack Russia then an assault on Singapore would be Hitler’s next preference. This was something he had been repeatedly urging for several months. At a conference in March 1941, attended by Hitler, Admiral Erich Raeder stated that “Japan must take steps to seize Singapore as soon as possible, since the opportunity will never again be as favourable”.

But the Tripartite Pact didn’t require either side to disclose their plans to the others. Japan, therefore, was under no obligation to warn Germany in advance. As one of the key elements of the Pearl Harbour attack was surprise clearly Japan would want to limit to number of parties who knew about it. However, there were strong hints.

In early November 1941 the German ambassador in Japan had warned Berlin that was was imminent. That was the first clue. But perhaps the key one was the amendment of the Tripartite Pact so that parties would be obliged to support each other even if one of them initiated hostilities. This amendment took place, at Japan’s insistence, just days before the Pearl Harbour attack.

It’s worth writing out the timeline of events and when you see the timeline you can see that Germany and Hitler probably knew a lot more about Pearl Harbour than is widely appreciated. These events are largely take from Ian Kershaw’s excellent biography of Hitler.

21 November Ribbentrop outlines the Germany policy that if either country was at war with the US the others would not make a separate peace.

23 November German ambassador, Ott, is asked about Germany’s position if Japan instigated an attack on the US.

24 November German ambassador sends a telegram to Ribbentrop informing him of the request. There is no record of a reply.

28 November Ribbentrop assures the Japanese ambassador Ōshima that they would come to Japan’s aid if they were at war with the US.

singapore_1941_1942 — Source: Singapore 1941-1942: Revised Edition By Louis Allen

4 December German and Japanese ambassadors make an amendment to the Tripartite Pact after consultation with Hitler. The amendment says that countries will support each other even if one of the parties attacks the US. The agreement was actually still unsigned when the attack took place.

7 December Japanese attack on Pearl Harbour.

11 December Germany, Italy and Japan sign a revised Tripartite Pact. Hitler makes a speech at the Reichstag declaring war on the US.

It’s seems clear therefore that Hitler and Germany knew that a Japanese attack was imminent possibly days away. However, there is also strong evidence that Hitler did not know the precise date or location of the Pearl Harbour attack. This can be surmised from his behaviour after Pearl Harbour.

Firstly, immediately after he found out about the attack he phoned Goebbels to let him know. If Hitler had known about the attack in advance he would presumably have letGoebbels know probably even bragged about it. Based on Goebbels’ diary entry he didn’t.

Secondly, Hitler delayed a speech at the Reichstag in order to ensure that the revised agreement for the Tripartite Pact was in place. This was the agreement which said that all parties would support the others even if they initiated an attack. If he had known the details of the attack in advance then presumably he would have organised his speech beforehand.

To conclude, therefore, it seems that Hitler did not know the precise details about the Japanese attack on Pearl Harbour. He certainly didn’t know the date and almost certainly didn’t know the intended target.

What he did know, however, is that hostilities were about to commence between Japan and the US and that they would be initiated by Japan. Despite being preoccupied with the Russian campaign the hints dropped by the Japanese, the messages from the German Ambassador and signing of an amended pact could have left him in little doubt that an attack was imminent.

The next question is, given that the Japanese attack would certainly mean war between German and the US how did Hitler feel about that and what implications did it have on his existing campaigns. That will be the subject of another post.

To find out more about this subject take a look at our timeline of the Second World War. Also checkout the resources below:

Wikipedia links:

Hitler by Ian Kershaw. A tremendous biography of Hitler. Read our full review here.

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