Choe U vs Kang Kam-chan

Choe U succeeded his father Choe Chung-heon as head of the military regime, maintaining control over Goryeo through puppet kings. He continued the family's authoritarian rule, suppressing any opposition.

Choe U refused Mongol demands for submission and tribute, leading to a series of Mongol invasions. His defiance prolonged the war but ultimately resulted in devastating campaigns against Goryeo.

Choe U moved the Goryeo court to Ganghwa Island to escape Mongol attacks, using the island's natural defenses. This allowed the regime to continue resistance but left the mainland vulnerable to Mongol raids.

Choe U died, and his son Choe Hang succeeded him. However, internal divisions weakened the regime, leading to its eventual collapse in 1258 and the restoration of royal authority under Mongol influence.

During the Second Goryeo-Khitan War, Kang Kam-chan successfully defended the fortress of Heunghwajin against a Khitan siege. His stubborn resistance bought time for Goryeo to regroup and negotiate a truce.

King Hyeonjong appointed Kang Kam-chan as supreme commander of Goryeo's forces during the Third Khitan War. This appointment gave him authority over all military operations and reflected the king's trust in his strategic abilities.

General Kang Kam-chan led Goryeo forces to a decisive victory over the Khitan Liao dynasty at Gwiju. The battle ended the Third Goryeo-Khitan War, with Goryeo inflicting heavy casualties and forcing the Khitan to withdraw permanently.