Beginning in the summer of 1018, the Liao dynasty constructed a bridge across the Yalu River. In December 1018, 100,000 Liao soldiers under the command of General Xiao Baiya crossed the bridge into Goryeo territory, but were met by an ambush of Goryeo soldiers. King Hyeonjong had heard the news of invasion, and ordered his troops into battle against the Liao invaders. General Gang Gam-chan, who did not have any military experience since he was a government official, became a commander of the Goryeo army of about 208,000 men (the Liao still had advantages, even outnumbered 2 to 1, since Liao troops were mostly mounted while the Koreans were not), and marched toward Yalu River. The Liao troops pushed through to approach Kaesong, the capital, but were defeated by a force led by General Gang Gam Chan.