Jiang Wei's 253 Northern Expedition is a failed Shu campaign whose shifting fortunes expose the vulnerability of coalition warfare to deception. Jiang Wei secures the participation of King Midang and the Qiang tribes, but Wei commander Chen Tai infiltrates that alliance through a feigned defection. Midang is captured, persuaded to abandon Shu, and released by Guo Huai; the former allies then attack the Shu camp, forcing Jiang Wei to retreat. The expedition ends in defeat, though Xu Zhi and Guo Huai are both killed, and the Wei victory helps consolidate Sima Shi's power.

Background and Coalition

In AD 253, Jiang Wei again assembles Shu forces and marches toward the Wei border. This time, the campaign is supported by the Qiang tribes, drawn into the invasion through gifts. King Midang joins with his army, making the expedition a coalition effort rather than a Shu advance alone.

Wei answers by sending Xu Zhi, renowned for his courage, to command its army. Sima Zhao accompanies him. The first engagement favors Wei: Xu Zhi inflicts heavy losses on Shu. The reversal in the next encounter, where Wei suffers and Xu Zhi is killed, gives Jiang Wei's forces an opportunity to press forward and overwhelm the Wei camp.

The Battle and the Qiang Reversal

Sima Zhao and six thousand men take refuge on a hill where a small spring cannot provide enough water for the troops. With supplies exhausted and morale sinking, Sima Zhao recalls a story of an earlier hero trapped without water who prayed to a spring and saw it gush forth. He makes offerings and prays in the same way; the stream then provides enough water for his men. In the account, this episode marks a desperate pause in a campaign otherwise turning against Wei.

The more consequential reversal comes through Chen Tai's deception. He pretends to desert with five thousand Wei soldiers and join Jiang Wei's alliance with the Qiang. Trusting the apparent defection, Midang orders a night attack on the Wei camp. A senior Qiang commander leads the assault with Chen Tai, but the attack becomes a trap: the commander's horse falls into a deep pit, the supposed defectors strike the Qiang from behind, and Chen Tai leads another Wei detachment against them from the front. Thousands of Qiang troops die, and Midang is captured.

Retreat and Political Consequences

Guo Huai releases Midang from captivity and persuades him to leave the alliance with Shu and return to his former Wei allies. The change in allegiance turns the campaign decisively. Midang's forces join an attack on the Shu camp, catching its troops by surprise and overwhelming them. Jiang Wei retreats, but wounds Guo Huai as he withdraws; Guo Huai dies that night.

The armies then fall back. Jiang Wei has lost the campaign, although the deaths of Xu Zhi and Guo Huai mean that his advance has inflicted consequential losses on Wei. Sima Zhao celebrates the repulse, and the victory strengthens the political position of his brother Sima Shi. The account links the expedition's military outcome to the balance of power at court: success against Shu adds to Sima Shi's authority, until he behaves as though he were emperor even in the emperor's presence.