Around the new year 352, Huan, impatient after his requests to advance north in light of Later Zhao's collapse were being rebuffed by Sima Yu and Yin, who were concerned about his expanding power, and mobilized his troops and gestured as if he were about to attack the capital. Yin was shocked, and initially considered either resigning or send the imperial banner of peace (Zouyu Fan, 騶虞幡) to order Huan to stop. After advice from Wang Biaozhi (), however, he instead asked Sima Yu to write a carefully worded letter to Huan, persuading Huan to stop.