The Sueojangdae Post is a two-story military facility that was used as a lookout post and for directing battles. The defense commander post was built on the western side of Namhansanseong Fortress as one of the four command posts around the fortress. Namhansanseong is a fortress city situated on Namhansan 500m above sea level and 25km southeast of Seoul. It was designated as a Provincial Park on March 17, 1971 as well as a UNESCO World Heritage site in June 2014. Sueojangdae has been very influential in Korea’s military history. During the Manchu Invasion of 1636, King Injo commanded troops from the defense commander post. The troops held out for 45 days against a Qing force of 120,000 until they were forced to surrender.