暗渡陈仓

Origin and story

The historical basis is in the Shiji (史記), volume 8. After being assigned Hanzhong, Liu Bang's forces destroyed the plank roads behind them, helping signal that he did not intend to return east. Later, following Han Xin's advice, he moved back by the old route and attacked Zhang Han, whose troops met him at Chencang and were defeated.

The famous fuller formulation pairs openly repairing the plank road with secretly advancing through Chencang. That vivid deception belongs to the later telling; the cited Shiji passage does not describe a public repair operation as a diversion. The idiom, also written 暗度陈仓, now describes carrying out a hidden plan under cover of an apparent one.