At the time of writing, Hung Hsiu-chu, the presidential candidate of Taiwan’s Kuomintang, is facing a challenge from members of her own party. Nominated in July as KMT’s pick for the island’s presidential elections in January, Hung’s dismal showing in recent opinion polls has prompted some of her party’s members to call for another candidate.

Pre-modern China’s imperial succession was based on primogeniture – the oldest son of the emperor’s principal wife, the empress, was the heir. The crown prince’s position, however, was never guaranteed. A common reason for a crown prince’s replacement was the emperor’s affections for another consort and, by extension, her son. Sometimes, greater forces were at work, involving political alliances and military backing cultivated by different princes.

In the case of Li Chengqian, the oldest son and crown prince of Emperor Taizong, of the Tang dynasty, the circumstances leading to the loss of his title were rather unusual. While Li was married with sons of his own, it is said he was deeply in love with Chengxin, a handsome teenaged boy entertainer. When the emperor found out about the affair, he was furious and had Chengxin executed. Emperor and crown prince became estranged and the latter began plotting an armed revolt to overthrow his father. The plot was uncovered and Li was demoted in AD644 and died of natural causes the following year.