King Geunchogo, the 13th ruler of the Baekje Kingdom, was undoubtedly one of the greatest figures of the kingdom, which enjoyed its glory days under this king in the mid-4th century. In addition to massive territory expansion, the king is highly credited with strengthening royal power and promoting maritime trade with neighboring states. Thanks to his remarkable achievements both inside and outside the nation, Baekje was able reach great heights earlier than the other two states on the Korean Peninsula during the so-called Three Kingdoms period.
Based on strong national power, Geunchogo conquered small tribes and town states. In 369, Baekje annexed the Mahan tribe to dominate the southwestern part of the Korean Peninsula. It also exerted great influence on the ancient Gaya confederacy states located west of the present-day Nakdong River in the southeastern region. As a result, Baekje emerged as a strong power that controlled the central and southwestern parts of the peninsula. Still, it had another rival, namely, the northern kingdom of Goguryeo.
In 369, the two states fought the battle in Chiyang in today’s Hwanghae Province in western North Korea. Baekje won the battle in a surprise attack and captured 5,000 enemy soldiers. At the time, Baekje was in fact behind Goguryeo in many ways—population, territory and the number of troops. Nevertheless, the former was able to defeat the latter, thanks to King Geunchogo’s great leadership and his troops that moved in perfect order. After losing the war, Goguryeo again attacked Baekje in 371. Again, Baekje’s ambush operations proved successful and the Goguryeo army retreated. In winter of that year, Geunchogo launched a counterattack, leading 30-thousand troops himself. The Baekje forces dominated most parts of the present-day Hwanghae Province and moved forward to invade Pyongyang Castle. Although Baekje failed to take the fortress and retreated, King Gogukwon of Goguryeo was shot by an arrow and killed in this battle. This was an incredible humiliation for Goguryeo, while Baekje fully demonstrated its power.
After the battle, Baekje secured a significant amount of land, including all of Gyeonggi Province, the central Chungcheong Province, the southwestern Jeolla Province, the northwestern Hwanghae Province and part of eastern Gangwon Province as well. In other words, Geunchogo gained supremacy over the Korean Peninsula and Baekje’s dominance over the regions culminated under the warrior king’s reign.