Siege of Chencang

The Siege of Chencang was the second Northern Expedition led by Shu-Han's chancellor, Zhuge Liang, to invade rival state Cao-Wei. 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.

Background
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, hoped to use this opportunity to launch an incursion into Wei territory. 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.

Prelude
After his failure on Mount Qi and Jieting, Zhuge Liang indeed changed his target to Chencang as Cao Zhen reckoned. Thoroughly prepared, the Shu Chancellor brought with him a selection of siege weapons and an expedition force of one hundred thousand men. Although a few officers including Wei Yan recommended an alternate route, Zhuge Liang was determined to follow Jialing Valley, which emerges in the north where the Wei River widens considerably near the city of Chencang. Zhuge Liang planned to capture Chencang as a midpoint for further military actions against the great metropolis Chang'an.

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 and replied, "what I said earlier remains solid. As I know you, my arrow doesn't." Upon hearing this, Zhuge commenced the offensive.

Siege
The odds were drastically against Hao Zhao&mdash;he only had 1,000 men at the time, while the Shu army, numbering 100,000, had established three layers of siege. Therefore, the Shu Chancellor aimed to take the fortress directly; he carried out an escalade tactic through the use of siege ladders, but Hao Zhao countered with fire arrows, burning the platforms and parching the men upon them. While the ladders were still aflame, Zhuge's battering rams designed to breach the city-gate had arrived, and Hao Zhao hurriedly chained some great stones and rolled them down, smashing the rams. The quick response and leadership of Hao Zhao shocked Zhuge Liang, as the latter never forejudged such a determined resistance.

Zhuge Liang then drew back and rethought on his tactic. Since moats made access to the walls difficult for siege weapons, which needed to be brought up against a wall to be effective, the Chancellor decided to remove the trenches to create more possible attack points. Following Zhuge's order, the besiegers started to fill the chasms and prepared their siege towers. With the ditches removed, the siege engines moved upon the castle while foot-soldiers climbed the walls like ants. However, Zhuge Liang was outwitted by Hao Zhao that when the former laid his hand on the entrenchment, the latter had already seen through his intention and started building interior walls inside the original walls. As long as the siege towers could not pass the first walls, the soldiers on top of the towers who managed to overcome the outer walls could not climb the second inner walls. Trapped inside the two gates of walls, those soldiers who descended from the towers became easy target for archery practice.

Suffering another defeat, Zhuge Liang adopted an architectural approach by asking his soldiers to dig tunnels that led to the substructure of the fortress. However, his method was actually different to the more common mining tactic, which is to excavate beneath the foundations of the walls, and then deliberately collapsing or exploding the tunnel&mdash;it is recorded that the Chancellor wanted to create some underground passages for his armies to enter the city directly in order to catch his opponent off guard. Zhuge Liang's tactic is a much perilous approach, because defenders can counter-tunnel to cut into the attackers' works and topple them prematurely, killing anyone affected by the collapse, and that is just what Hao Zhao did.

The struggle had been continuing non-stop for 20-odd days and nights, with Zhuge Liang straining his tactics to no avail. News came of Wei reinforcements being led by Zhang He was a serious threat to Zhuge Liang, especially when the latter started to face logistic difficulty, so the Shu army retreated. Seeking glory, a Wei general, Wang Shuang, led his cavalry in pursuit of the enemy to the Qinling Mountains, where he fell into an ambush planted by Zhuge Liang and was killed. On the other hand, Zhang He precisely predicted Zhuge Liang would retreat before he even arrived Chenchang, so Zhang He headed Nanzheng, but was not able to catch up with Zhuge Liang.

Aftermath
Scoring such a victory, Hao Zhao instantly became a celebrity, and an imperial decree was passed down to grant the victor a title of marquis. Cao Rui also summoned Hao Zhao to the capital of Luoyang, where the young emperor praised his general highly. However, Hao Zhao soon died of illness during his stay in the capital.

In the same year of 229, Zhuge Liang launched his third expedition. This time, he again changed his target, sending Chen Shi to besiege Wudu and Yinping commanderies. The Wei general, Guo Huai, ceded the two commanderies to Shu Han, in fear he would be sandwiched by Chen Shi and Zhuge Liang.

Modern references
The Siege of Chencang is featured as a playable stage in the fifth installment of Koei's video game series Dynasty Warriors 5.