in 9 CE, Wang Mang, the usurper, forced the Han empress dowager to hand over the Seal. The empress dowager, in anger, threw the Seal on the ground, chipping one corner. Later, Wang Mang ordered the corner to be restored with gold. This Seal passed on even as dynasties rose and fell. It was seen as a legitimizing device, signalling the Mandate of Heaven. During turbulent periods, such as the Three Kingdoms period, the seal became the object of rivalry and armed conflict. Regimes which possessed the seal declared themselves, and are often historically regarded, as legitimate. At the end of the Han dynasty in the 3rd century AD, General Sun Jian found the Imperial Seal when his forces occupied the evacuated Han imperial capital Luoyang, in the course of the campaign against Dong Zhuo, giving it to his chief, warlord Yuan Shu. The Romance of the Three Kingdoms says that one of Sun Jian's men betrayed him and told about the Seal to the coalition leader Yuan Shao who asked him for the seal, but Sun Jian refused. He swore that if he had the Seal, he might die a violent death, and set out for his home. Nevertheless, Yuan Shao told Liu Biao to block his way; Liu Biao did so, though he was unable to defeat Sun Jian. This began a rivalry between them, and Sun Jian, according to his oath, died a violent death in an ambush while fighting Liu Biao later on. Sun Jian's son, Sun Ce inherited the seal and gave it to Yuan Shu so that he might lend him troops to take revenge for his uncle, who had been fighting Warlord Lu Kang. Yuan Shu then declared himself emperor under the short-lived Zhong dynasty in 197. This act angered the warlords Cao Cao and Liu Bei, leading to several crushing defeats by each army. The other warlords, even after being issued with an imperial decree, refused to help Cao Cao and Liu Bei in defeating Yuan Shu. When Yuan Shu was defeated in 199 by Liu Bei, the Seal came into the hands of Cao Cao, whose son Cao Pi proclaimed the Wei Dynasty as the legitimate successor state to Han, in 220, in response to the established states of Shu Han and Eastern Wu. The Seal remained in the hands of Wei Dynasty emperors until the last emperor Cao Huan was