bīng yǐ yì dòng 兵以义动
Fighting for a Righteous Cause
This term means sending an army to fight a just war, similar to the present idea of “fighting for righteousness.” Since ancient times, the Chinese people have held high esteem for an army sent to war for the sake of justice. Here yi (义) means stopping any aggressive act of violence, and eliminating the suffering of the people. War is an act of violence, and no one should initiate a war. Instead, war is a last resort to resist and prevent any violence inflicted on the people. The term demonstrates the ideals of justice and benevolence upheld by the Chinese nation.
An army that fights to quell violence and rescues people from peril is called an army of justice. (Wuzi)
An army is used to subdue riots, not to start any violent action. (Huainanzi)
Now we launch an army to fight for a righteous cause. If we hesitate and do not take actions right away, we will disappoint the whole nation. (The History of the Three Kingdoms)