The Seosansung Fortress located in Okcheon is widely postulated to be the historical site of the “Gwansansung Fortress”, renowned for its connection to “Gwansansung Battle” in the year 554. Positioned as the principal entryway to the Okcheon basin, this fortress stands as a highly significant relic, esteemed for its role as a pivotal defensive bastion within the ancient Okcheon region.
This study examines the geographical placement and environmental context of Seosansung Fortress in Okcheon. Through an analysis of historical records and geographical documentation, it briefly delves into the rationale behind proposing Okcheon Seosansung area as the plausible location for Gwansansung Fortress. Additionally, the study introduces the archaeological achievements and significant revelations brought forth by the precise archaeological surface survey carried out at Seosansung Fortress in Okcheon.
Based on the this survey, the perimeter of Seosansung Fortress is approximately 1,025m, with a surface area of 31,727 square meters. This survey method divided the fortress wall into four segments, with cross-sectional measurement points strategically placed at intervals of 20 to 40m, which allowed the discernible cross-sectional shape of the wall to be identified.
Regarding the infrastructure within the fortress, three gateways, six building structures, one defensive castle, and one water collection facility are presumed to be present. The assessment of these fortress facilities involved a meticulous examination encompassing visibility analysis and slope direction analysis to gain an overarching understanding of the fortress's condition. Notably, the visibility analysis validated the military domination of Seosansung Fortress, overseeing the expanse of the Okchen Basin. This positioning showcases an interconnected dynamic with the nearby Samyangri Earthen Wall Fortress and the Samgeori Earthen Wall Fortress, situated within a 500-meter radius, indicative of an interdependent relationship.
Artifacts excavated from Seosansung Fortress in Okcheon span diverse historical epochs, ranging from earthenware and roof tiles indicative of the Three Kingdoms period to white porcelain and roof tiles characteristic of the Joseon Dynasty. Aligning these findings with records in the “Sejong Sillok Jiriji (Geographical Records in the Annals of King Sejong)” and “Sinjeung Dongguk Yeoji Seungnam (Revised Edition of the Augmented Survey of the Geography of Korea)”, this evidence suggests that the fortress has been operational from the Three Kingdoms period through the Joseon Dynasty. Given the expansive flatland and size of the fortress, this exploration presents a compelling indication that it might have functioned as the Chiso(治所) Fortress in ancient times.