Empress Lü Zhi
When the Han court began to purge former supporters of Xiang Yu, Zang Tu became fearful and rebelled. Liu Bang as the Emperor Gaozu personally led a campaign against Zang Tu in Ji. Zang Tu was defeated and killed in 206BC. Emperor Gaozu appointed his childhood friend Lu Wan as the Prince of Yan. In 195BC, he became distrustful of Lu Wan and invaded Ji. Lu Wan fled to the Xiongnu in the steppes. To tighten control of the region, the Emperor Gaozu sent his son Liu Jian to Ji as the Prince of Yan. After Liu Jian died in 181BC, Gaozu's widow, the Empress Lü Zhi controlled the Han court, and made her nephew Lü Tong as the Prince of Yan. When Empress Lü Zhi's regency ended in 179BC, Liu Ze became the Prince of Yan and his family ruled Ji for three generations.