By 1935, Germany had ceased to recognize the Treaty of Versailles and all the restrictions that accompanied it. In particular, Hitler announced his intention to fully rebuild Germany’s military forces. In 1938, Germany began annexing the territories of neighboring countries, including all of Austria and most of Czechoslovakia. When Germany attacked Poland in September 1939, Britain and France aligned against Germany, and the war began.
-Like Germany, Japan was severely affected by the Great Depression. Japan relied heavily upon imported resources and desperately needed more land for its expanding population. Japanese military leaders, who at the time had a strong influence over the civilian government, saw territorial expansion as the best solution. As a result, beginning in 1931, Japanese forces began occupying territory in the Chinese region of Manchuria. By 1937, Japan and China were officially at war. In 1940, Japan signed a formal alliance with Germany and Italy, setting the country on a clear course to enter World War II.
-In the meantime, the United States, disapproving of Japan’s actions, placed a heavy trade embargo on Japan, severely restricting its ability to import oil, and other resources vital to its war effort. Japan saw itself facing an impossible crisis, and without prompt and decisive action, total collapse was inevitable. The action Japan chose was a surprise attack on the U.S. Naval base at Pearl Harbor, Hawaii, on December 7, 1941. This action brought the United States into World War II in both theaters, Europe and the Pacific.