 In 645, when Emperor Taizong commanded a major campaign against Goguryeo, he put Xiao in charge of Luoyang as well as the logistics of shipping supplies to the frontline.In 646, Xiao was again in discord with the other chancellors, going as far as accusing Fang of factionalism bordering on treason.Emperor Taizong was also displeased with Xiao over his requesting to become a Buddhist monk at one point around this time and then changing his mind.