 Emperor Wu commissioned Yuwen Xian with an army to suppress Yuwen Zhi's rebellion, although before Yuwen Xian could get back to Chang'an the rebellion was already put down by the official Yuchi Yun (尉遲運).In 575, Emperor Wu, secretly planning a major attack on Northern Qi, only conferred with Wang Yi (王誼) and Yuwen Xian while making his plans, and Yuwen Xian greatly supported the plan.Emperor Wu personally attacked Luoyang, but after sieging it for 20 days without capturing it, he grew ill and was forced to withdraw.