When Goryeo signed a treaty with the Mongols and returned its capital to Gaegyeong, the Sambyeolcho military corps refused to accept this and, under the command of Bae Jung-son, enthroned the royal relative Wang On as king and moved south to Jindo. There they built a palace and fortress, naming it Yongjangseong, and used it as a base to continue their resistance against the Mongols from 1270 to 1271.
Even as the royal court chose surrender, those who came down to this island chose a different path. That their resistance ultimately ended in defeat does not diminish the weight the choice itself carried. What remains of the fortress today is the trace of people who chose the difficult path of resistance over the easier path of surrender.