During the Warring States Period, the State of Zhao had a famous general named Zhao She. His son, Zhao Kuo, was an avid reader of military texts and loved discussing strategy. He could recite military classics from memory and debated warfare with such clarity and logic that he even seemed to surpass his father in theoretical knowledge.
When the State of Qin attacked Zhao, the king ordered Zhao Kuo to lead an army of 400,000 men to resist the invasion. However, having no practical battle experience, Zhao Kuo was decisively defeated and lost his life.
This story gave rise to the idiom "armchair strategist," used to describe someone who is skilled only in theory but lacks practical experience.