Germany

The Second World War is usually regarded as having started on 1 September 1939 with the invasion of Poland by Germany. There is much truth to this perception, although Japan had already clashed with Russia earlier that summer and had been fighting in China since 1937. The difference is that the invasion of Poland was fought on a total war basis, while the conflicts in Asia were kept limited by tacit agreement among the powers involved.

The United States were strongly isolationist and unwilling to intervene in the European war. However, the Japanese attack on Pearl Harbor, followed three days later by declarations of war from Germany and Italy, meant that the United States would fight against the Axis with all of their considerable industrial potential.

The Allied Powers agreed that Germany was the greatest threat and had to be defeated first. In retrospect, this “Germany First” policy was unquestionably correct, but it was controversial at the time with the American public, who were inflamed by the Pearl Harbor attack and inclined to give higher priority to the Pacific theater. Eventually a formula was settled on in which 30% of Allied resources would go to the Pacific and 70% to Europe until Germany was defeated. The U.S. Air Force was scrupulous about this agreement, allocating almost precisely 30% of its squadrons to the Pacific. However, the latest model aircraft almost always went to Europe first. The U.S. Army was a little more flexible; in the early days of the war, when Japan was on the rampage in the Pacific, more Army troops went to the Pacific than to Europe. Later the allocation of divisions approached the 70/30 ratio. The U.S. Navy never took the 70/30 formula very seriously, partly because the Army adamantly refused to accept Marine divisions for service in Europe, and partly because the Pacific was a naval theater while Europe was a continental theater, apart from the U-boat war (which required a different force composition than the Pacific campaigns.) The naval allocation of manpower to the Pacific was never less than 50%.

The actual German presence in the Pacific was never more than token. A few U-boats operated in the Indian Ocean, a few auxiliary cruisers made calls at Japanese ports, and some blockade runners carried supplies to and from the Far East, but that was about all.

It need not have been that way. Historian H.P. Willmott has argued that Japan's only real prospect for winning the Pacific War lay in an offensive across India into the Middle East to shake hands with German forces. However, the Japanese army, preoccupied with China and the possibility of a Russian collapse, was unwilling to support extended operations into the Indian Ocean.

References

Willmot (1982)