Sima Yu
In 350, Yin himself prepared a campaign north, but failed to immediately carry out that campaign; instead, he seized even more power after accusing Cai, by repeatedly declining an honor conferred on him, was being disrespectful to the emperor, and reducing Cai to commoner status. Meanwhile, Huan became impatient after his requests were being rebuffed by Sima Yu and Yin and, around the new year 352, Huan 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.