Battle of Hulao

Battle of Hulao
Part of the transition from Sui to Tang
Map of the situation in China during the transition from the Sui to the Tang, with the main contenders for the throne and the main military operations
Date 28 May 621 Location Hulao Pass, Henan Result Decisive Tang victory, end of Xia and surrender of Luoyang
Belligerents
Tang Dynasty	Xia
Commanders and leaders
Li Shimin	Dou Jiande  (POW)
Strength
50,000 in total, less than half at Hulao	100,000–120,000
Casualties and losses
	3,000 killed ca. 50,000 taken captive

The Battle of Hulao (虎牢之戰) on 28 May 621 was a decisive victory for the Tang Dynasty prince Li Shimin, through which he was able to subdue two rival warlords, Dou Jiande and Wang Shichong. The battle was fought at the strategically important Hulao Pass, east of Luoyang. Li Shimin led a siege on the city of Luoyang, seat of the self-declared emperor Wang Shichong, who solicited help from Dou Jiande from the east. However, Dou Jiande delayed and when he finally arrived, Li Shimin brought forces to meet the new threat. Li Shimin's army avoided conflict until the troops of Dou Jiande were exhausted and then led a cavalry charge, breaking the opposing army and capturing Dou Jiande. Afterwards, Wang Shichong, seeing no other choice, surrendered Luoyang, and both his and Dou Jiande's states were absorbed by the Tang. Dou Jiande was later executed, resulting in some of his followers, led by Liu Heita, raising an unsuccessful rebellion against the Tang. Hulao marked the decisive turning point in the civil wars that followed the collapse of the Sui Dynasty, after which the eventual victory of the Tang was never in doubt.

During the later reign of the second emperor of the Sui Dynasty, Yang (reigned 604–618), the dynasty's authority began to wane: the immense material and human cost of the protracted and fruitless attempts to conquer the Korean kingdom of Goguryeo, coupled with natural disasters, caused unrest in the provinces, while the successive military failures eroded the emperor's prestige and legitimacy ("Mandate of Heaven") among the provincial governors. Yang nevertheless continued to be fixated on the Korean campaigns, and by the time he realized the gravity of the situation, it was too late: as revolts spread, in 616, he abandoned the north and withdrew to Jiangdu, where he remained until his assassination in 618.

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