of 20,000 Jiangnan troops was defeated by Cao Bin. Song forces continued to advance and reached the outskirts of Jinling in March 975. No defensive preparations were made by Li Yu. Both he and his court officials foolishly felt existing fortifications were adequate enough to keep the Song at bay. Starting in April the capital was put under siege by Cao Bin. In January 976 Li Yu surrendered outside his palace. He and his remaining courtiers kneeled down at the feet of Cao Bin. The deposed ruler reached Bian in February. The imperial portrait of Li Bian produced by Zhou Wenju was presented to Taizu. This measure signified the complete submission of Jiangnan to the Song. Jiangnan was formally annexed and dissolved by the Song. The newly incorporated territories had 650,565 registered families. Lu Jiang acting Military Governor of Zhaowu Circuit continued to resist Song army after seizing She Prefecture before persuaded to surrender; Jiangnan general Hu Ze who was stationed at Jiang Prefecture refused to surrender to Song and continued to resist until his failure in May. In 978 Li Yu died probably from actual illness, rather than being poisoned on the command of Taizu as some accounts claim. Historiography Song historians tended to favor presenting the Five Dynasties as passing on the mandate of heaven in a linear fashion to the succeeding dynasty. The Song were at the end of this process, gaining the mandate from the Later Zhou. This logic, which did not factor the Southern Tang or other states, was critical to Song claims of legitimacy. Other states of the period like the were seen not in possession of the mandate and therefore entirely illegitimate. Song histographers likewise disregarded the Southern Tang and its potential "as a southern alternative to empire building." The Jiu Wudai Shi was released in 974 and is the earliest work to deal with the Southern Tang. It was composed to justify Song political pretensions. Li Yu still ruled as a vassal of Taizu and so was excluded from the work. The Southern Tang was denounced as a state of "usurpation and thievery" or jianqie 僭竊. Rulers were generally referred to using the word 偽 to label them as swindlers. Despite these ideological attacks, the work accurately recorded political events between the Central Plain dynasties and the Southern Tang. The Jiangnan lu 江南錄 was written on the order of Emperor Taizong, the