Joseph Warren "Vinegar Joe" Stilwell was a United States Army general who served in the China Burma India Theater during World War II. Stillwell was made the Chief of Staff of the Chinese Nationalist Leader, Chiang Kai-shek. He spent the majority of his tenure striving for a 90-division army trained by American troops and equipped with American lend-lease and fighting to reclaim Burma from the Japanese. His efforts led to friction with Chiang who viewed troops not under his immediate control as a threat and who saw the Chinese communists as a greater rival than Japan. An early American popular hero of the war for leading a column walking out of Burma pursued by the victorious Imperial Japanese Armed Forces, his implacable demands for units debilitated by disease to be sent into heavy combat resulted in Merrill's Marauders becoming disenchanted with him. The U.S. government was infuriated by the 1944 fall of Changsha to a Japanese offensive. Stilwell delivered a message to the Chinese Nationalist leader, Chiang Kai-shek from President Roosevelt that threatened that lend-lease aid to China would be cut off. The resulting friction atop an already tense relationship made Ambassador Patrick J. Hurley advocate that Stilwell had to be replaced. Chiang had been intent on keeping Lend-Lease supplies to fight the Chinese Communist Party, but Stilwell had been obeying his instructions to get the Communists and the Nationalists to co-operate against Japan.

China Burma India Theater (CBI) was the United States military designation during World War II for the China and Southeast Asian or India–Burma (IBT) theaters. Operational command of Allied forces in the CBI was officially the responsibility of the Supreme Commanders for South East Asia or China. In practice, U.S. forces were usually overseen by General Joseph Stilwell, the Deputy Allied Commander in China; the term "CBI" was significant in logistical, material and personnel matters; it was and is commonly used within the US for these theaters.