Original: Battle of Tumu Fortress: The Oirat Mongols defeat the  Ming Dynasty army and capture the Zhengtong Emperor of China; the latter is officially deposed while his brother ascends as the Jingtai Emperor the next year.
Simplified: Ming Dynasty army and capture the Zhengtong Emperor of China; the latter is officially deposed while his brother ascends as the Jingtai Emperor the next year in 1450.