▁request ▁to ▁allow ▁additional ▁Mong ol ▁en vo ys ▁to ▁China ▁and ▁a ▁Chinese ▁prin cess , ▁Es en ▁decided ▁to ▁in va de ▁the ▁M ing . ▁T ais un ▁Khan ▁was ▁app reh ensive ▁of ▁this ▁and ▁did ▁not ▁support ▁Es en ▁at ▁first . ▁However , ▁he ▁was ▁induced ▁to ▁lead ▁the ▁eastern most ▁force ▁of ▁Uri ank h ais ▁to ▁L ia od ong ▁in ▁ 1 4 4 9 . ▁He ▁bes ie ged ▁the ▁city ▁and ▁rav aged ▁its ▁out sk ir ts ▁for ▁ 4 0 ▁days ▁while ▁Es en ▁cr ushed ▁the ▁M ing ▁arm ies ▁en ▁route ▁to ▁Be ij ing . ▁ ▁After ▁defe ating ▁the ▁M ing ▁army ▁during ▁the ▁T um u ▁Cris is ▁and ▁capt uring ▁the ▁Zh eng t ong ▁Emperor ▁the ▁Mong ols ▁returned ▁north . ▁T ais un ▁Khan ▁treated ▁the ▁captured ▁em peror ▁kindly . ▁Upon ▁real izing ▁that ▁the ▁M ing ▁would ▁not ▁pay ▁a ▁r ans om ▁for ▁the ▁captured ▁em peror , ▁the ▁Zh eng t ong ▁Emperor ▁was ▁returned ▁in ▁ 1 4 5 0 . ▁ ▁Dec line ▁ ▁T ais un ▁Khan ' s ▁cons ort , ▁the ▁elder ▁sister ▁of ▁Es en , ▁attempted ▁to ▁persu ade ▁the ▁k han ▁to ▁make ▁his ▁sister ' s ▁son ▁the ▁designated ▁he ir . ▁The ▁request ▁was ▁denied , ▁causing ▁T ais un ▁and ▁Es en ▁to ▁go ▁to ▁war ▁in ▁ 1 4 5 1 . ▁Es en ▁promised ▁T