Former Yan
In 369, the paramount Jin general Huan Wen launched a major attack against Former Yan, reaching Fangtou (枋頭, in modern Hebi, Henan), in the vicinity of Former Yan's capital Yecheng. In panic, Former Yan sought assistance from Former Qin, promising that if Former Qin launched troops to assist, it would cede the Luoyang region to Former Qin. Most Former Qin officials opposed, but Wang advised Fu Jian that he had to make sure that Huan would not conquer Former Yan—because Former Qin would not be able to stand up to Jin if Jin destroyed Former Yan. Fu Jian thus launched troops, which arrived after Former Yan's general Murong Chui had already dealt Huan one defeat, but the Former Qin forces, in conjunction with Former Yan, did deal Huan another major defeat. However, Former Yan reneged on its promise to cede the Luoyang region, and Fu Jian put Wang in charge of a 60,000-men force against Former Yan. Wang's campaign seemed even more promising after Murong Chui, fearful of Murong Ping's jealousy and the emperor Murong Wei's mother Empress Dowager Kezuhun's hatred toward him, defected to Former Qin.