Jangsu of Goguryeo - Northwestern Campaign

Northwestern Campaign

At the time China was invaded by five foreign races and divided into Sixteen Kingdoms. Later Yan Dynasty, which was based on present-day Liaoning Province, was defeated so heavily by Gwanggaeto the Great's forces and finally came to an end in 408. After the fall of Later Yan, Han Chinese drove Murong clan of Xianbei northward and established Northern Yan Kingdom in the area. However, Northern Yan was no match for Xianbei Northern Wei Dynasty, which unified most of northern China. Then Northern Yan began to seek alliances with Goguryeo, which had greater power than itself and which also can fight equally against Northern Wei. In 436 Goguryeo cavalry arrived in Northern Yan and eventually drove Xianbeis away.

Song Dynasty during the era, which was in the feud against Northern Wei, encouraged both Northern Yan and Goguryeo as rivaling nations of Northern Wei. However, the plan did not work out all right as Jangsu turned against them and destroyed Northern Yan in 438. He conquered the entire region and held its ex-king as captive. Song court was outraged and warned King Jangsu that the death of Yan king means the war between two nations; However Jangsu ignored the warning and executed the king. Song troops then attacked Goguryeo but were easily defeated. The peace resumed in the following year when Jangsu sent 800 horses as gift to the Song Emperor, to prepare for the war against Northern Wei, so Goguryeo can concentrate its forces against Baekje and Silla while two Chinese powers were in war against each other. Jangsu again encouraged Song to invade Wei in 459 when he sent loads of crossbows and provided gold and silver. Wei government was upset by his actions but had to keep peace with Goguryeo to continue war against Song and Rouran. Jangsu also seek relationship with Wei to wage war against Baekje, so the two empires established formal relationship in 435.