Japanese invasion of the United States (Napoleon's World)

The 1925 Japanese invasion of the United States was a Pacific War military operation undertaken by Japanese Imperial forces in the spring and summer of 1925 in an attempt to force an early peace with the United States. With as many as 4,500,000 troops involved in the invasion, as well as over a thousand naval vessels and three thousand supporting aircraft, it was the largest single military operation in human history. Despite overwhelming numbers and early victories in California, the greater strategic goal of forcing an American capitulation was not achieved, and after the repulsion of Japanese forces in Oregon and the Colombian victory at Panama, the invasion of the United States was unsustainable and Japanese forces had withdrawn completely by the end of January 1926.

While regarded as a strategic failure, the invasion is regarded as an impressive initial success, due to the relative maintenance of the Japanese supply lines across the Pacific Ocean throughout 1925, the subjugation of the American Naval presence in the Pacific through the seizure of or destruction of major American ports and naval bases, the interference with the crucial economic supply lines in the western United States, in particular California, and the sheer size of an invasion force establishing a foreign foothold so far away from home.

The Japanese invasion of the United States was a crucial component of the North American theater of the Pacific War.