运筹帷幄 — “To devise strategies within a command tent”

In the early Western Han Dynasty, after the empire had been unified, Emperor Gaozu Liu Bang held a grand banquet in Luoyang's Nangong. After several rounds of wine, he posed a question to his officials: 'Why did I achieve victory, and why did Xiang Yu fail?' Gao Qi and Wang Ling suggested that Emperor Gaozu succeeded because he assigned talented individuals to capture cities and strategic locations, and rewarded those who made great contributions, thus enabling him to achieve great things. Xiang Yu, on the other hand, did the opposite; he failed to reward those who made achievements and mistrusted capable people.

Liu Bang listened and agreed that their points were valid, but emphasized that the most crucial reason for his victory was his ability to employ capable individuals. He then praised Zhang Liang, saying: 'To devise strategies within a command tent and ensure victory a thousand miles away, I am not as skilled as Zifang (Zhang Liang's courtesy name).'

This statement highlighted Zhang Liang's profound strategic thinking, his clever use of intellect, and his mastery of military tactics.