The Japanese land invasion of British Burma, which began in mid-January of 1942, may not figure prominently in the general history of the Pacific War or for that matter, the subsequent routing of the Japanese armed forces in this particular theater. But the strategic importance of the Burma campaign can be hardly understated. The Japanese prospects for victory over China had turned into a distant hope rather than an imminent reality by the fall of 1939, as Japan failed to capitalize on its initial gains. Britain, France, the Soviet Union, and the United States, meanwhile, had begun actively supporting the Chiang Kai-shek Government by offering an array of economic and military aid shortly after the outbreak of the Sino-Japanese armed conflict in July 1937. The aid thus rendered included allowing passage of supplies to Chongqing through land routes via British Burma and French Indochina. Once drawn into the war against the Axis Powers in December 1941, the United States heightened its commitment to maintaining ground- and air-based supply lines in support of Chiang Kai-shek through the China-Burma-India (CBI) borders, so that China might eventually be utilized for the bombing of the Japanese homeland. The war in two theaters now intricately connected, Japan had to find ways to interrupt the supply routes in the southern border region of China, isolate the Nationalist Government, and put an end to the prolonged conflict against China. In short, the war in British Burma came to constitute the heart of the Pacific War rather than a sideshow.