Kim Yu-sin and the Unification of the Three Kingdoms: Silla's General, His Horse and the Battle of Hwangsanbeol

Kim Yu-sin (595–673) was a Korean general and statesman of seventh-century Silla who led the unification of the Korean Peninsula under Silla during the reigns of King Muyeol and King Munmu; he is the most famous of all the generals of the wars that ended Korea's Three Kingdoms period. Throughout his life he believed that Baekje, Goguryeo and Silla should not be separate countries but one, and he is regarded as the driving force behind their unification.

A family from fallen Gaya

Kim Yu-sin was the son of General Kim Seohyeon and Lady Manmyeong, a member of Silla's royal family. His father's line, the Gimhae Kim clan, descended from the royal house of Geumgwan Gaya, a small kingdom that had been absorbed by Silla; it traced its roots back to the legendary founder Suro. This mixed background gave him both noble connections and something to prove.

The hwarang and the horse

As a young man Kim Yu-sin became a leader of the hwarang, Silla's elite youth corps, which combined military training, moral education and religious practice. A famous story about his youth shows his strict self-discipline. Once he spent the night at a courtesan's house, and his mother wept and begged him never to go there again. One night, very drunk, he fell asleep on his horse, and the horse carried him to the same house out of habit. When he woke and saw where he was, he was so angry at having broken his promise that he killed the horse. The story is told in Korea as a lesson about keeping one's word.

A family alliance

Kim Yu-sin's sister Mun-hee married his close friend Kim Chunchu, who later became King Taejong Muyeol of Silla; their son became King Munmu. This marriage tied the warrior and the statesman together. Kim Chunchu handled diplomacy, including the alliance with Tang China, while Kim Yu-sin led the armies. Together they set Silla on the road to unification.

Hwangsanbeol: the last stand of Gyebaek

In 660, Silla and its Tang allies attacked Baekje. At Hwangsanbeol, Kim Yu-sin's army met the Baekje general Gyebaek, whose force of about 5,000 men faced roughly ten times as many Silla soldiers. Gyebaek's men fought bravely, and the battle became famous in Korean memory as a heroic last stand, but Baekje, already weakened by internal problems, collapsed. Goguryeo fell in 668.

Driving out Tang

Victory over Baekje and Goguryeo did not end the struggle. Tang China wanted to control the peninsula itself, and Silla had to fight a difficult war against its former ally. Eventually Silla forced out the Tang troops and united the peninsula under its rule. Kim Yu-sin's second son, Kim Won-sul, later played a central role in securing Silla's independence from Tang.

Honours and legend

In 668 King Munmu gave Kim Yu-sin the unique honorary title Taedaegakgan, the highest rank in Silla. He lived to the age of 79 and died in 673. He is remembered as one of Korea's greatest generals and sword masters, and he is the subject of countless stories and legends that most Koreans learn as children. Many of these legends, such as claims of heavenly signs at his birth, were seen even by the medieval historian Kim Busik as strange and hard to believe.

How Koreans remember him

Kim Yu-sin's tomb stands on a wooded hillside in Gyeongju, the old Silla capital, ringed by stone panels carved with the twelve animals of the zodiac. Visitors still come to pay their respects. His life also raises questions that Koreans continue to debate: was Silla's unification a true joining of peoples, or the victory of one kingdom with foreign help? Did the alliance with Tang China cost the peninsula the northern lands that Goguryeo had once held? Teachers often use Kim Yu-sin and Gyebaek side by side, the winner who united the land and the loser who fought to the end, to show that history can honour both determination and loyalty. Whatever one's view, his story remains one of the great founding tales of Korean history.

Learn with Kim Yu-sin: Korean words

Korean	Meaning	Example
통일 (tongil)	unification	신라가 삼국을 통일했어요.
장군 (janggun)	general	김유신은 장군이었어요.
약속 (yaksok)	promise	약속을 지켜요.
말 (mal)	horse	말을 타고 갔어요.
화랑 (hwarang)	Silla youth corps	화랑은 무예를 익혔어요.

Try this: Write three English sentences about a promise you kept, then one Korean sentence with 약속.