三十六计 Thirty-Six Stratagems: 明修栈道，暗度陈仓 Openly repair the gallery roads, but sneak through the passage of Chencang
Chapter 2: Enemy Dealing Stratagems 敌战计
The phrase originated from the Chu-Han contention (楚汉之争 ChǔHànzhīzhēng), where Liu Bang (刘邦 Liú Bāng) retreated to the lands of Sichuan to prepare for a confrontation with Xiang Yu (项羽 Xiàng Yǔ). Once he was fully prepared, Liu Bang sent men to openly repair the gallery roads (栈道 zhàndào) he had destroyed earlier, while secretly moving his troops towards Guanzhong through the small town of Chencang (陈仓 Chéncāng) instead. When Xiang Yu received news of Liu Bang repairing the gallery roads, he dismissed the threat since he knew the repairs would take years to complete. This allowed Liu Bang to retake Guanzhong (关中 Guānzhōng) by surprise, and eventually led to his victory over Xiang Yu and the birth of the Han Dynasty.
This tactic is an extension (延伸 yánshēn) of the "Make a sound in the east, then strike in the west" tactic. But instead of simply spreading misinformation to draw the enemy's attention, physical baits (诱饵 yòuěr) are used to increase the enemy's certainty on the misinformation. These baits must be easily seen by the enemy, to ensure that they draw the enemy's attention. At the same time, the baits must act as if what they meant to do what they were falsely doing, to avoid drawing the enemy's suspicion.