Shut the Door to Catch the Thief

If you have the chance to completely capture the enemy then you should do so thereby bringing the battle or war to a quick and lasting conclusion. To allow your enemy to escape plants the seeds for future conflict. But if they succeed in escaping, be wary of giving chase.

Warring States Era China

    In 449 BC the state of Wu had invaded the state of Yue and carried off its duke Guo Jian holding him prisoner for three years before releasing him back to his kingdom. When he returned Guo Jian planned his revenge. For seven years he ruled with benevolence and generosity making a reputation as a wise and virtuous ruler until he felt his loyal subjects were prepared to undergo any hardship for him. He accordingly assembled his forces and attacked Wu gaining a decisive victory. The king of Wu had to flee but it would only be a matter of time before he was caught. He sent ambassadors to Guo Jian begging for mercy. They reminded him of how Wu, though she had him firmly in her grasp, had released him to return to his state. The king of Wu now asked to be granted the same favor. Guo Jian was contemplating granting this appeal when his prime minister Fan Li intervened and said: "When heaven gave the duke of Wu the grand opportunity for gaining power he did not take advantage of it and so he is a fugitive today. Should you fail to accept what fortune has now given you, you may be driven from your state, and then all the years of hardships you have bourn will have been endured in vain." The duke was swayed by the argument and sent the ambassador back with the message that he would not grant any mercy. When the king of Wu received the message he gave up all hope and committed suicide.