The Siege of Chencang was the second Northern Expedition led by Shu-Han's chancellor, Zhuge Liang, to invade rival state Cao-Wei, in an attempt to relieve Wei's pressure on Wu's Jingzhou after the Battle of Shiting. The campaign became a siege on a fastness at Chencang from December 228 to early 229 during the Three Kingdoms period of Chinese history. The expedition concluded with Shu-Han retreat.

In 228, after Eastern Wu defeated Cao Wei at the Battle of Shiting, Wei reinforced the east by mobilizing its troops in the west. Shu Chancellor and regent, Zhuge Liang, decided to attack Wei to divert its attention back to the west and relieve pressure for Shu Han's ally. Before the Chancellor finalized an operation plan, Cao Zhen of Wei had distinctly anticipated Zhuge's route of advancement and recommended Hao Zhao to build fortifications for Chencang. The Supreme General, Cao Zhen, assured the young emperor Cao Rui of the defence against probable invasions from Shu. However, Hao Zhao was only assigned 1,000 men for his task. The prognosis was made after Zhuge Liang had lost the first expedition earlier that year.

After his failure on Mount Qi and Jieting, Zhuge Liang indeed changed his target to Chencang as Cao Zhen reckoned. Intent for a quick expedition, the Shu Chancellor brought with him a selection of siege weapons. Zhuge Liang hoped the attack on Chancing would alert Wei enough to move its force back to Guanzhong from Jingzhou.

The Shu army reached the fortress-city of Chencang during December 228, wherein the defense was apparently not completed as Cao Zhen had not sent additional forces to move in. Having completed the encirclement, Zhuge Liang sent Jin Xiang, a personal friend of Hao Zhao, to convince the latter to defect. The first time the two friends spoke, Hao Zhao would hear none of it, saying "The law of Wei is what you practiced; the nature of me is what you know. I have received so much from my country and I can't let down on my family. You ought to say no more, I'll only die defending this city. The lobbyist told Zhuge Liang what Hao Zhao had said, and again Zhuge sent Jin Xiang to soften the steadfast defender. "Our armies are enormous while you only have a tiny force, what good is it to perish for a futile effort?" said Jin Xiang outside of the city-gate. This time, however, Hao Zhao fitted an arrow to his bow and replied, "What I said earlier remains solid. I know you, but my arrow doesn't", implicitly threatening to kill Jin Xiang. Upon hearing this, Zhuge commenced the offensive.

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