Pacific War:

In August 1943 the Allies formed a new South East Asia Command (SEAC) to take over strategic responsibilities for Burma and India from the British India Command, under Wavell. In October 1943 Winston Churchill appointed Admiral Lord Louis Mountbatten as its Supreme Commander. The British and Indian Fourteenth Army was formed to face the Japanese in Burma. Under Lieutenant General William Slim, its training, morale and health greatly improved. The American General Joseph Stilwell, who also was deputy commander to Mountbatten and commanded U.S. forces in the China Burma India Theater, directed aid to China and prepared to construct the Ledo Road to link India and China by land.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". Who was deputy commander to Mountbatten?
General Joseph Stilwell