于禁 / Yu Jin
于禁 / Yu Jin first appears in the Wancheng branch through Hanji 1013, where he arrives after 曹操 escapes and defeats 张绣’s continued pursuit. The source uses him as the force that prevents the disaster from becoming total collapse.
于禁 / Yu Jin enters the wiki through Hanji 1014 as 曹操’s 平鲁校尉 during the Wancheng retreat. While Cao Cao’s force is disordered, Yu Jin keeps his own troops controlled and suppresses plundering by Qingzhou soldiers attached to Cao Cao’s army.
His most important choice in the source is procedural. After the Qingzhou soldiers complain to Cao Cao first, Yu Jin does not rush to defend his reputation. He assumes pursuit may still come, organizes defensive works, and only then explains the facts. The episode uses this to define 临危先务军纪: in a crisis, military order and camp security outrank personal vindication.
Cao Cao praises Yu Jin for settling disorder and securing the camp under extreme pressure, then rewards him as 益寿亭侯. In the source’s reading, Yu Jin’s value lies in combining discipline, public-order concern, and trust that Cao Cao can distinguish evidence from slander.