Chu Suiliang, and Ma Zhou, to serve as Li Zhi's friends and advisors. As Crown Prince Late in 643, Emperor Taizong issued an edict to select beautiful women among good households to serve as Li Zhi's concubines. However, after Li Zhi declined such treatment, Emperor Taizong cancelled the edict. However, during his years as crown prince, he was said to have favored his concubine Consort Xiao, having two daughters (the later Princesses Yiyang and Xuan Cheng) and one son (Li Sujie) with her, much to the chagrin of his wife Crown Princess Wang, who was childless and jealous of Consort Xiao. Three other concubines of his bore his other sons Li Zhong, Li Xiao (), and Li Shangjin (). Around the same time, however, Emperor Taizong also became concerned that Li Zhi, who was considered kind but weak in character, would not be strong enough to be an emperor, and secretly discussed with Zhangsun Wuji the possibility of making another son by his concubine Consort Yang (daughter of Emperor Yang of Sui), Li Ke the Prince of Wu, crown prince. Zhangsun repeatedly opposed the idea, and Emperor Taizong did not carry this out. In 645, when Emperor Taizong launched a campaign against Goguryeo, he took Li Zhi with him to Ding Prefecture (定州, roughly modern Baoding, Hebei) and then left Li Zhi there to be in charge of logistics, before heading to the front himself. He also left senior officials Gao Shilian, Liu Ji, Ma Zhou, Zhang Xingcheng, and Gao Jifu to assist Li Zhi. After the campaign ended in failure later that year, as Emperor Taizong was leading the army back from the front, Li Zhi went to meet him at Linyu Pass (臨渝關, now Shanhai Pass). Emperor Taizong suffered an injury during the campaign, and Li Zhi was said to have, as Emperor Taizong's conditions were getting worse, sucked the pus out of his wound, until Emperor Taizong recovered somewhat. In 646, with Emperor Taizong still recovering, he transferred some of the imperial authorities to Li Zhi. Li Zhi stayed at the imperial palace and attended to Emperor Taizong in his illness. That year, when Emperor Taizong was due to visit Ling Prefecture (靈州, roughly modern Yinchuan, Ningxia) to meet with a number of tribal chiefs who were formerly vassals of Xueyantuo—which had collapsed under Tang and Huige attacks earlier that year—he was set to take Li Zhi