An Qingxu
In 758, however, Shi Siming, possibly because of a failed assassination plot against him, possibly at the order of Emperor Suzong and the prominent Tang general Li Guangbi, turned against Tang again and initially aided An Qingxu, then under Tang siege at Yecheng. In spring 759, Shi Siming was able to have the siege against Yecheng lifted, and then, when An Qingxu met him to thank him, killed An Qingxu. He left Shi Chaoyi in defense of Yecheng and returned to Fanyang. Later that year, when Shi Siming claimed the title of emperor of Yan, he created Shi Chaoyi the Prince of Huai, but did not create him crown prince. Rather, he created his wife, Lady Xin, empress, and favored her son, Shi Chaoqing (史朝清), considering creating Shi Chaoqing crown prince. In summer 759, when Shi Siming launched a major campaign against Tang's eastern capital Luoyang, he left Shi Chaoqing in charge of Fanyang and joined forces with Shi Chaoyi and other Yan generals. He captured Luoyang quickly, but was subsequently repelled in his attempt to attack the Tang capital Chang'an, as he was unable to capture Shan Prefecture (陝州, roughly modern Sanmenxia, Henan).