Even when, for example, King Xi of Zhou used his royal clout to give legitimacy to Wu of Quwo as the rightful duke of Jin in 678 BCE, succession issues continued to arise.
[2] At the same time that the Jin duke was conquering new lands, a process of "subinfeudation" or "rear vassalage" occurred in the early and middle parts of the Spring and Autumn period, wherein aristocratic title and territory were awarded to vassals loyal to Jin, rather than to the Zhou royalty.
[6] In one extreme case, Viscount Xian of Xi, a retainer of Duke Jing of Jin, attempted to invade the state of Qi with only the troops under his command.
[12] In the leadup to the civil war, the dominant clans were the Zhao, Wei, Han, Fan (范), Zhi (智) and Zhonghang (中行) who were collectively called the "Six Titled Retainers" (Chinese: 六卿; pinyin: Lìu Qīng).
Zhaozi of Fan, who intermarried with Zhonghang clan, was also concerned with Zhao's imprudence on the matter of Handan's execution.
Jianzi of Han, Xiangzi of Wei and Wenzi of Zhi invaded Zhonghang and Fan's fief under the name of Duke Ding of Jin.
Wenzi of Zhonghang and Zhaozi of Fan eventually lost their struggle against Han, Zhao, Wei and Zhi.
After the battle, Zhonghang and Fan fled to Chao Ge while Jianzi of Zhao returned to the state of Jin.
The Handan conflict led to the decline of Zhonghang and Fan clan which prepared the way for the formation of Han, Zhao and Wei's hegemony in Jin's court.
[14] Fan clan's resistance in Chao Ge was supported by Zhou dynasty, Qi, Lu, Wey and Zheng.
Faced with a critical situation, Zhao Xiangzi sent an envoy who persuaded the Han and Wei clans to change sides.
As their respective powers were so balanced, none of the three remaining aristocratic families felt they could feasibly gain an upper hand over the others.
[17][18] All three states quickly formed strong bureaucracies,[19] thereby weakening the potential for any aristocratic families from encroaching on their power.