The United States Army Transportation Corps (USATC) S200 Class is a class of 2-8-2 steam locomotive. They were introduced in 1941 and lent-leased to the United Kingdom for use in the Middle East during World War II.
At least 85 S200s operated in the Middle East, including Egypt, Palestine and Lebanon. One was destroyed by fire at El Arish in Egypt in 1942. 29 of this batch was later supplied to Turkey where they became the TCDD 46201 Class. In 1946 another 24 were transferred to TCDD which added them to the same number series 46201–46253. 51 S200s built in 1942 served on the Trans-Iranian Railway, where they became Iranian class 42.
Thirty were donated to China by the UNRRA. China Railways designated these as class ㄇㄎ10 （MK10） in 1951, then reclassifying them as class 解放10 (JF10, Jiefang, "Liberation") and numbering them 3711−3740.