The siege of Kuju (Korean: 귀주성전투) which occurred in 1231 was a decisive Goryeo victory against the Mongol Empire.
After the Mongol army crossed the Yalu river, it quickly captured almost all of Goryeo's border defenses.
[1] The Mongol army, however, ran into stiff resistance both at Anju and the city of Kuju (modern-day Kusong), commanded by General Park Seo.
The Mongols deployed special assault teams who manned siege towers and scaling ladders.
Pak Seo and Ch'oe Ch'unmyŏmg, defender of Chaju, were almost executed but the Mongols spared them owing to their courage, which they admired.