dukedom, and in 419, after he was created the Prince of Song, Liu Yifu was given the special honor to be known as Crown Prince of Song. It was also around this time that he married Emperor Gong of Jin's daughter Sima Maoying the Princess Haiyan. During Emperor Wu's reign After Liu Yu seized the throne from Emperor Gong and established Liu Song (as its Emperor Wu) in 420, he created Liu Yifu crown prince. By 422, Emperor Wu was ill. His official Xie Hui saw that Crown Prince Yifu was often spending time with people lacking in abilities and virtue, and warned Emperor Wu about it. Emperor Wu considered making Liu Yizhen the Prince of Luling crown prince instead. Xie, however, after meeting with Liu Yizhen, had an even worse opinion of Liu Yizhen, and so Emperor Wu stopped considering so. As Emperor Wu grew seriously ill later that year, he entrusted Crown Prince Yifu to Xu Xianzhi, Fu Liang, Xie Hui, and Tan Daoji. At the same time, however, he secretly warned Crown Prince Yifu that Xie was such a quick thinker that he could not be trusted greatly. He then died, and Crown Prince Yifu took the throne as Emperor Shao. Reign Emperor Shao honored his stepgrandmother Xiao Wenshou as grand empress dowager, and he created his wife Crown Princess Sima Maoying as empress. The matters of the central government were largely in the hands of Xu Xianzhi, Fu Liang, and Xie Hui. One immediate matter that needed to be dealt with was that Emperor Mingyuan of Northern Wei, hearing of Emperor Wu's death, launched a major attack on Liu Song and crossed the Yellow River. In winter 422, Northern Wei forces captured Huatai (滑台, in modern Anyang, Henan). In spring 423, they captured Luoyang. Tan Daoji was dispatched to try to save the northern cities, and he was able to save Shandong Peninsula from falling, but by summer 423, the last major Liu Song outpost on the Yellow River, Hulao (虎牢, in modern Zhengzhou, Henan), had fallen, along with Xuchang. Only then did Northern Wei stop its advances. In fall 423, Emperor Shao honored his mother Consort Zhang as empress dowager. By 424, Xu, Fu, and Xie had grown increasingly dissatisfied with Emperor Shao as an emperor, as Emperor Shao had failed to follow the proper behavior during the three-year mourning period for his father, but