In December 1440 Mu Ang petitioned for a second campaign involving a combined army of at least 120,000 men from
Huguang,
Sichuan, and
Guizhou. The Vice Minister of Justice, He Wenyuan, was against a second campaign and petitioned the court on 7 February 1441, in an attempt to persuade them not to squander their resources in capturing land that is "not inhabitable to us." The war party, led by the Minister of War, Wang Ji, and the Duke of Yingguo, Zhang Fu, argued that to let Si Renfa do as he pleased would show weakness to the neighboring Hsenwi and Ava, and would result in a loss of prestige and encourage further rebellions. The second campaign was authorized by the young Zhengtong Emperor under the influence of the palace eunuch
Wang Zhen. The second expedition was led by Jiang Gui, Li An, Liu Ju, and Wang Ji. Before the expedition was carried out, Liu Qiu, a member of the
Hanlin Academy, as well as an imperial tutor, presented a memorial in opposition of the campaign. Liu Qiu argued that the southern rebels had already retreated into hiding in the southernmost zone of Yunnan, and did not warrant such a large expenditure as mobilizing 150,000 men. Wang Zhen had him arrested and executed by dismemberment. The second Ming campaign to the Yunnan frontier was officially launched on 27 February 1441. In June 1441, a Ming contingent of 8,000 engaged with a small Mong Mao party and defeated them in battle, inflicting 150 casualties. In September 1441, the Ming army met with a Mong Mao force of 30,000 and 80 elephants. The Mong Mao advance was repelled, suffering 352 casualties. In November 1441, a Ming army of 20,000 was ambushed by Si Renfa. However the ambush was unsuccessful and Si Renfa was forced to retreat with 1,000 casualties. The Ming army pursued the defeated Shan forces to their stronghold in Shangjiang and besieged them. When the Ming set fire to their stockades, Si Renfa's forces attempted to escape through a watergate, but were attacked by the Ming, and suffered heavy casualties. Although Si Renfa managed to escape, his side reportedly suffered 50,000 casualties in total. In December 1441, a Ming contingent of 8,000 engaged in battle with an armed Mong Mao force of 20,000 and defeated them. In January 1442, the Ming army finally attacked Si Renfa's base and captured it. The defending garrison was said to have suffered 2,390 casualties. Si Renfa fled to
Ava where he was arrested by the king and held for ransom in return for Ming land, however the Ming were reluctant to deal with Ava. == Third campaign (1443–1444) ==