While King Gwanggaeto was able to bring the entire Korean Peninsula under control effectively, he never neglected his territory expansion to the north. It would be fair to say that his conquest of the northern regions better illustrates his bravery and greatness. From the ninth year of the king’s reign in 400, Goguryeo constantly engaged in battles with Later Yan founded by one of the Xianbei tribes in present-day Liaoning Province. When Later Yan attacked Goguryeo in 400, King Gwanggaeto successfully drove the enemy forces out of his territory. After several more fierce battles, Goguryeo was able to overpower Later Yan and take the entire Liaodong Peninsula. The region continued to remain a territory of Goguryeo until the kingdom collapsed in the late 7th century when the Tang Dynasty of China took control of the area.
In the 20th year of his reign, in 410, the king conquered Sushen and East Buyeo in the northeast. East Buyeo was simply no match for the strong Goguryeo army and finally surrendered. Now, King Gwanggaeto occupied the Manchurian region. His military campaign was not over yet. Goguryeo also expanded further to the northwest and defeated Kitan people, who were living along the Shara-muren River Valley in present-day Inner Mongolia. This shows that Goguryeo expanded its territory as far as the northeastern part of Inner Mongolia.
The king died in 413 at the age of 39. He ruled his kingdom for only 22 years and unfortunately died quite young, but he made incomparably brilliant achievements to write a glorious history of conquests. He chose Yeongrak as a title for his era for the first time in Korean history. It is viewed as a symbolic move to raise the status of Goguryeo rulers to that of Chinese monarchs.
The power of Goguryeo reached its peak during the era of his son and successor, King Jangsu. In recognition of his father’s outstanding achievements, King Jangsu erected a memorial stone in 414 at the site of King Gwanggaeto’s tomb in Jian in Jilin Province in northeast China, which was the capital of Goguryeo at the time. The 6-meter-high monument, the largest engraved stele in the world, was rediscovered by a Chinese scholar in 1875. The Gwanggaeto Stele records entire battles waged by the king with some 1,800 Chinese characters. Unfortunately, not all characters were preserved. For Korean people, King Gwanggaeto the Great was a more heroic conqueror than Alexander the Great, and the stele is an invaluable historical asset that provides important information about the king’s reign.
The expansionist kingdom of Goguryeo recalls the images of galloping horses and a vast extend of land. Goguryeo was indeed a warrior state that stretched Korea’s borders to their widest point ever in history. Much of the credit should go to King Gwanggaeto the Great, who gave his people not only a large territory but peace and stability as well. There is no doubt that Goguryeo dominated East Asia as a great power under the king. He is remembered by Koreans as one of the greatest figures in their history.