origin : https://en.wikipedia.org/wiki/Gim_Yu-sin
Gim Yu-sin (595 – 18 August 673), also known as Kim Yu-sin, was a general in 7th-century Silla. He led the unification of the Korean Peninsula by Silla under the reign of King Muyeol of Silla and King Munmu of Silla. He is said to have been the great-grandchild of King Guhae of Geumgwan Gaya, the last ruler of the Geumgwan Gaya state. This would have given him a very high position in the Silla bone rank system, which governed the political and military status that a person could attain.
Much of what is known about Gim's life comes from the detailed account in the Samguk Sagi, Yeoljeon 1-3, and the much briefer record in the Samguk Yusa, vol. 1.
Early years[edit]
Gim Yu-sin was the son of General Gim Seohyeon (the second son of General Gim Mu-ryeok) and Lady Manmyeong, who was a daughter of Gim Sukheuljong (Hangul: 김숙흘종; Hanja: 金肅訖宗, King Jinheung of Silla's younger brother). He was born in Gyeyang, Jincheon County in 595, became a Hwarang warrior at just 15 and was an accomplished swordsman and a Gukseon (Hangul: 국선; Hanja: 國仙; Hwarang leader) by the time he was 18 years old. By the age of 34 (in 629) he had been given total command of the Silla armed forces. Three years later, Gim Yu-sin's cousin, Princess Deokman, became Queen Seondeok of Silla and kept Gim Yu-sin as commander in chief of the royal army. During the reign of Queen Seondeok of Silla (632-647), Gim Yu-sin owned ten thousand private soldiers, won many battles against Baekje and became one of the most powerful man in Silla.
Military accomplishments
Yushin's first military engagement in command is believed to have occurred around 629 AD, and through it he quickly proved his capabilities as a warrior. Silla was in a constant struggle with its neighbor to the west, Baekje, over territory. There had been gains and losses on both sides, and the struggle lasted for many years. It was during this period that Yushin rose through the ranks of the military, rising to the position of general and becoming a skilled field commander.
Baekje and Shilla had formed an alliance to counter Goguryeo's power and its intentions to push southwards, and together they launched a successful attack on it, Silla taking the northern territory and Baekje the one south of the Han river. But Silla broke the alliance and attacked Baekje in order to claim both territories for itself. After this betrayal, Baekje allied with Goguryeo. When Goguryeo and Baekje attacked Silla in 655, Silla joined forces with Tang Dynasty China to battle the invaders. Although it is not clear when Gim Yu-sin first became a general, he was certainly commanding the Silla forces by this time. Eventually, with the help of the Silla navy and some 130,000 Tang forces, Yushin attacked the Baekje capital, Sabi, in 660, in one of the most famous battles of that century, the Battle of Hwangsanbeol.
The Baekje defenders were commanded by none other than General Gyebaek, although the Baekje forces consisted of about 5,000 men and were no match for Yushin's warriors, which numbered about ten times as many. Baekje, which had already been experiencing internal political problems, crumbled. Gim Yu-sin's Silla forces and their Tang allies now moved on Goguryeo from two directions, and in 661 they attacked the seemingly impregnable Goguryeo kingdom, but were repelled. The attack had weakened Goguryeo, though. In 667 another offensive was launched which, in 668, finally destroyed Goguryeo.
Silla still had to subdue various pockets of resistance, but their efforts were then focused on ensuring that their Tang allies did not overstay their welcome on the peninsula. After some difficult conflicts, Silla eventually forced out the Tang troops and united the peninsula under their rule
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