Koryo-Khitan war begins

1010

A Khitan Liao invasion of Korea under Emperor Shengzong overwhelmed the Korean border and captured the capital at Kaesong, forcing King Hyeonjong to flee south. The Koreans eventually rallied and drove the invaders out with heavy losses, but Korean-Khitan conflict would sputter on for another decade. The invasion prompted Goryeo to begin constructing a massive defensive wall across the northern frontier.