fearful that such a plot would again develop during the midst of a Northern Wei invasion, Emperor Wen would, against promises he made to his older sister Liu Xingdi the Princess Kuaiji, have Liu Yikang killed. In 446, when Northern Wei was facing a rebellion from the ethnically-Xiongnu Gai Wu (), Emperor Wen commissioned Gai as a duke and a general, although he provided no actual military support for Gai. This, however, aggravated Northern Wei's Emperor Taiwu, and after Emperor Taiwu put down Gai's rebellion, the relationship between the two states turned sour, particularly in light of a horrific raid that Northern Wei troops carried out against Liu Song's Qing (青州, modern central and eastern Shandong), Ji (冀州, modern northwestern Shandong), and Yan (兗州, modern western Shandong) Provinces later that year. By 449, Emperor Wen was preparing a second campaign to recover the provinces south of the Yellow River, and many generals and officials, in response, submitted battle plans, and the general Wang Xuanmo () submitted plans that Emperor Wen particularly liked. In preparation, Emperor Wen moved the troops stationed and supplies stored in the internal provinces to the boundary provinces. Meanwhile, however, before he could launch the campaign, Northern Wei's Emperor Taiwu invaded first in spring 450, putting Xuanhu (懸瓠, in modern Zhumadian, Henan) under siege for 42 days, and after much loss on both sides, Emperor Taiwu withdrew without having captured Xuanhu. This made Emperor Wen believe that Northern Wei's military power was waning, and he decided to launch his attack late in 450, despite oppositions by the generals Liu Kangzu (), who believed that the campaign should begin in spring 451, Shen Qingzhi (), who opined that Liu Song was not in shape to fight a war against Northern Wei, Xiao Sihua, and Crown Prince Shao. The Liu Song forces, under the commands of Xiao Bin () and Wang Xuanmo, quickly took Qiao'ao and Le'an (樂安, in modern Tangshan, Hebei), as Northern Wei forces abandoned those two cities quickly, and then put Huatai under siege. The Han people around Huatai were initially gladly supporting the Liu Song campaign, but Wang ordered them to submit a large number of pears, causing them to be angry and turn against Liu Song. Liu Song forces, as a consequence, could not capture Huatai quickly, and in winter 450, Emperor Taiwu crossed the Yellow River, and Wang's forces collapsed, forcing him to