Gwangseongbo Fortress was the scene of some of the fiercest battles, particularly Sinmiyangyo, the American invasion in 1871. This fortress was renovated in 17th century after sustaining damage from several attacks. Gwangseong Dondae is one of three batteries that belonged to Fort Gwangseongbo is said to have been built in 1679. Ssangchung Stone Monuments were erected to honor 60 Joseon soldiers who died at the Battle of Gwangseongbo in the 1871. Gwangseongpodae Bulwarks was one of several defense installations built during the late Joseon period to guard the coastal areas of Ganghwado in 1874. Sondolmok Dondae Observation Post, built in 1679, originally comprised of one armory located in the center with three cannons. Yongdudondae Observation Post is a natural fortification used to guard the Ganghwa Strait. Serving as an outpost for the Sondolmok Fort, it doubled as a battery. This site was where the fierce battle during Sinmiyangyo (American Disturbance of 1871) took place.