Battle of Wuchang Plains
The Battle of Wuchang Plains was a major battle of the Three Kingdoms period of China. The battle was between the forces of Shu, led by Zhuge Liang, and the forces of Wei, commanded by Sima Yi. Sima Yi succeeded in repelling Zhuge Liang's forces; however, the Wei forces suffered massive casualties.
In 234, Zhuge Liang was planning a large campaign to conquer the Cao Wei kingdom. Liu Shan sent several scout forces to the border to probe for weaknesses in the enemy defenses. Cao Pi found one of the forces near modern-day Hanzhong and planned to move immediately to attack. However, on advice from Sima Yi, Cao Pi allowed the scouts to return and sent men to follow them back.
Zhuge Liang, suspecting that his plans had been discovered, sent for Zhao Yun to prepare a force immediately and advance. At the same time, Sima Yi gathered his own force and headed to Mianyang, where he suspected he would find the enemy camp. The two forces met at Wuchang Plains.
Zhuge Liang's army was considerably smaller; however, he also had access to Liu Shan's elite horsemen, which put him at an advantage in the open terrain. During the early days of the battle, Sima Yi took the defense, using archers to keep the horsemen at bay. Sima Yi hated fighting defensively, so he quickly devised plans to defeat the horsemen. He sent men to burn away the grass in the field. As the fighting dragged on, Zhuge Liang ran out of fodder for the horses; without graze land, the horsemen were forced to withdraw.
Zhuge Liang's Plot
By autumn, Zhuge Liang's illness was growing worse, a fact which was well known to Sima Yi. Zhuge Liang left a number of plots to Zhao Yun, with instructions on when to use them, and had his men stage a funeral for him. Sima Yi took advantage of his rival's apparent death, moving half his infantry to attack the enemy camp. As they neared the camp, they were ambushed by archers, suffering great losses. Rather than pulling back, Sima Yi called for the rest of his men to surround the camp and the ambush units.
The Shu army withdrew after five days of fighting. Zhuge Liang died of his illness during the fighting, just a few days after the fake funeral. Zhao Yun ordered the men to retreat while he stayed behind to slow the enemy.
Although the Wei army won the battle, they suffered massive casualties and lost their defensive position. This likely added to their eventual defeat.