Silla retaliation against the Protectorate's domination (668 - 676)
Silla retaliated against the Protectorate's domination by aiding Geom Mojam's rebellion in the north, and attacking Protectorate forces in Baekje territory. In 671 Silla seized Sabi Castle from the Tang armies. They overthrew the puppet government of Buyeo Yung which had been established there. Angered, Tang declared a younger brother of King Munmu to be Silla's rightful ruler, but was unable to follow this symbolic blow with a military one.
Facts and Events :
Nearly simultaneous with the collapse of Koguryo, Tang China moved to establish administrative control over the entire Korean peninsula. Emperor Gao Zong created the "Protectorate-General to Pacify the East" within the ruins of Pyongyang and established nine additional commanderies to govern Koguryo's former domain. It extended its jurisdiction over Paekche by establishing commanderies in each of Paekche's five provinces and creating the Great Commandery of Kyerim as a mechanism to control the Kingdom of Silla. King Munmu and the Silla court came to stark realization that Tang China was treating it no differently than it had been treated by Paekche and Koguryo.
The Chinese did not want to appear offensive to local residents, so they disguised the reality of their actions by appointing local rulers as governors in each of the commandery districts. They installed Prince Yung in Ungjin as territorial administrator of the former Kingdom of Paekche and appointed King Munmu as Governor-General of Kyerim to administer his own kingdom from Kumsong (modern Kyongju). Real control however, rested in the hands of General Liu Renyuan and the Tang Chinese army. Emperor Gao Zong never intended to win over the people of Korea, he real intent was to bring the entire Korean Peninsula under Chinese imperial control.
Unwilling to accept Chinese dominance, Silla launched a fresh campaign to assert its own dominance over the former Koguryo domain. Proving to be Koreans above all else, scattered remnants of Koguryo soldiers joined forces with Silla warriors to attack and destroy the token Chinese commandery garrisons. Silla sent its armies into the former kingdom of Paekche and defeated General Liu Renyuan's occupation armies in numerous battles. During one such engagement, General Kim Yu-sin ordered one of his generals to command what would certainly be a suicide attack against a large Chinese force. The officer accepted the order as a great honor and requested that General Kim watch over his only son to prevent him from following his father into battle. General Kim assured him that he would do so. The general rode into the fight and was quickly killed. Having witnessed his father's death at the hands of the Chinese, the young man broke free, mounted his horse and rode into battle. He too, died fighting. Almost immediately the slain general's house manager and personal servant mounted up and rode into battle, only to be killed. The entire Silla army witnessed this incredible act of loyalty. Swept with a wave of sympathy for this act of sacrifice, General Kim's army charged into battle to avenge the death of a general's entire family.
Silla retook the Pusosansong Fortress at Sabi in 671 AD, and regained control over the entire former territory of Paekche. China retaliated by sending a fresh army to punish the upstart kingdom, but after five years of raging combat Silla badly mauled the Chinese and succeeded in pushing them north of the Taedong River. Faced with stiff resistance in Korea, China relocated its office of the Protectorate-General to Pacify the East from Pyongyang to the city of Liaodongcheng near modern Liaoyang just south of Mukden, Manchuria, in effect recognizing Silla's hegemony over the Korean Peninsula. China gave up its drive for outright military subjugation of Korea and negotiated a truce line with Silla that extended roughly along the Taedong River across the peninsula to the Bay of Wonsan on the east coast. Whether intended or not, the truce line effectively recognized Silla's claim to political dominance over the entire peninsula.
Although Silla unified the peninsula only as far north as the Taedong River, there is great historical importance to what happened here. China's ambition to conquer not only Koguryo, but Paekche and Silla, threatened Korea no less severely than had the creation of the Four Han Chinese Commanderies nearly seven hundred years earlier. Silla's warriors preserved Korean independence by repulsing the Tang emperor's aggression with armed force. Silla not only resisted the Tang Chinese militarily, but actually held on to its independence from China. While Koreans may admire Koguryo for its strength and Paekche for its refinement, Silla alone seems to have been truly Korean. It was this territory, these people, and the society and the culture they fashioned for themselves in Unified Silla that became the foundation for the future independent development of society and culture in a unified nation.