to recall his sons Li Jiancheng, Li Yuanji (both by Duchess Dou) and Li Zhiyun (, by his concubine Lady Wan), whom he had left there to watch over his household, and the capital Chang'an (modern Xi'an) to recall his daughter (the future Princess Pingyang) and her husband Chai Shao (). Li Jiancheng and Li Yuanji, leaving Li Zhiyun at Hedong, soon met with Chai, and they arrived together at Taiyuan. Li Yuan's daughter, believing it would be difficult for her to flee with Chai, chose to hide instead. Once Li Jiancheng, Li Yuanji, and Chai arrived at Taiyuan, Li Yuan formally declared his rebellion, but maintained the guise of a Sui loyalist and declared that his intention was simply to install on the throne Emperor Yang's grandson Yang You, the Prince of Dai, who was then at Chang'an, and honor Emperor Yang as Taishang Huang (retired emperor). Li Yuan first secured his northern flank by contacting Shibi Khan, offering tribute, and received men and horses in exchange. He put Li Jiancheng and Li Shimin in charge of his army and, leaving Li Yuanji in charge at Taiyuan, advanced south. Meanwhile, the Sui officials at Hedong arrested Li Zhiyun and delivered him to Chang'an, where he was executed. His daughter Pingyang sold her possessions to raise an army for him. She persuaded several other leaders to fight under her banner. They took several towns and her army swelled until she had 70,000 troops under her command. Meanwhile, Li Yuan wrote another rebel leader, Li Mi the Duke of Wei, who was near Luoyang, trying to see if Li Mi would be willing to follow him, but Li Mi, believing in his own strength, had his secretary Zu Junyan () write Li Yuan for him in this way: Li Yuan was dismayed but, not wanting to make another enemy, wrote back humbly: Li Mi was pleased with Li Yuan's response, believing that Li Yuan was willing to support him, and from that point on, Li Mi and Li Yuan often exchanged messengers. Li Yuan's campaign against Chang'an thus went without opposition from Li Mi. Meanwhile, however, when Li Yuan arrived near Hedong, his army was bogged down by the weather, and with food running out, there were rumors that Eastern Tujue and Liu Wuzhou would attack Taiyuan. Li Yuan initially ordered retreat, but at the earnest opposition by Li Jiancheng and