X Force (Chinese Expeditionary Force)
X Force was the name given to the portion of the National Revolutionary Army's Chinese Expeditionary Force that retreated from Burma into British India in 1942. Chiang Kai-shek sent troops into Burma from Yunnan in 1942 to assist the British in holding back the Japanese.
Source: Wikipedia — X Force (Chinese Expeditionary Force) (CC BY-SA 4.0)