In fall 564, in order to placate Yuwen Hu, Emperor Wucheng of Northern Qi returned Yuwen Hu's mother Lady Yan and his (and Emperor Wu's) aunt (Yuwen Tai's sister), who had been trapped in Northern Qi territory several decades earlier, to Northern Zhou. In order to celebrate Lady Yan's return, Emperor Wu issued a general pardon, and prostrated himself before her as an ordinary nephew would. In turn, Yuwen Hu considered calling off planned joint attacks with Tujue against Northern Qi, but was fearful that Tujue would believe that Northern Zhou was abandoning the alliance, and therefore launched another joint attack with Tujue in winter 564. The assault, the main brunt of which was against Luoyang, however, was unsuccessful, and soon was abandoned.