In the late Western Han, Wang Mang usurped the throne and renamed the dynasty "Xin." His even harsher rule than the Western Han sparked peasant uprisings like the Green Woodsmen and Red Eyebrows. Distant imperial relatives Liu Yan and Liu Xiu seized the opportunity, mobilizing thousands of their clansmen and retainers to join the Green Woodsmen.
Liu Xiu and his brother Liu Yan, seeking to strengthen their forces, planned to ally with the peasant rebel army known as the Xiajiang Army, so they invited its commanders to discuss a grand strategy. After deliberation, the Xiajiang leaders Wang Chang, Cheng Dan, and Zhang Ang decided that Wang Chang would attend the meeting.
Liu urged Wang Chang to lead their troops together against Wang Mang and restore the Han dynasty. He said to Wang Chang, "If we succeed, we will share the fruits of victory together."
Wang Chang agreed and returned to relay Liu's words to Cheng Dan and Zhang Ang.
Cheng Dan and Zhang Ang said, "Our Xiajiang army has many troops—why should we unite with them? A true man acts on his own and should not be controlled by others!"
Wang Chang, determined to pledge allegiance to the Liu brothers, told the other generals, "Wang Mang has lost the people's support; everyone demands the restoration of the Han dynasty. Now that the Liu brothers of the Han imperial clan have raised troops, I believe allying with them will surely lead to great success."
The generals, who already held Wang Chang in high esteem, were swayed by his words and one by one declared their willingness to follow his command. Seeing this, Cheng Dan and Zhang Ang had no choice but to fall silent.
Therefore, Wang Chang led the Xiajiang army to join forces with Liu Yan and Liu Xiu's troops. Historical records later described them as "united in heart and mind, their fighting spirit growing ever stronger." Within days, they annihilated the armies of Wang Mang's generals Zhen Fu and Liangqiu Ci.
Later, the idiom "With One Heart and One Mind" came to describe people united in purpose and working together.
Source: *Book of the Later Han*, "Biography of Wang Chang"
Meaning of the Idiom: Later, the Chinese idiom "齐心同力" came to describe people united in purpose and working together.