Rebellion of the Three Guards
The Rebellion of the Three Guards (simplified Chinese: 三监之乱; traditional Chinese: 三監之亂; pinyin: Sānjiànzhī Luàn), or less commonly the Wu Geng Rebellion, was a civil war, instigated by an alliance of discontent Zhou princes, Shang loyalists, vassal states and non-Chinese peoples against the Zhou government under the Duke of Zhou's regency in the latter 11th century BC.
After the fall of the Shang dynasty, King Wu of Zhou had appointed his brothers Guanshu, Caishu and Huoshu as the "Three Overseers" of the East to secure the newly conquered Shang lands. After his death and King Cheng of Zhou's coronation, Wu's brother Duke Dan of Zhou declared himself regent and took over the court. This aroused the anger of the Three Guards who suspected Dan of usurpation and believed that they should serve as regents. Allied with many separatist eastern nobles, Shang loyalists under Prince Wu Geng, and several Dongyi and Huaiyi states, they rose in rebellion against the Duke of Zhou. The latter then launched a second "eastern campaign" to put down the rebellion, and defeated the rebels in three years, killing or disempowering their leaders. In doing so, he also further expanded the Zhou kingdom into eastern China, transforming it into an empire using the new Fengjian system.