When the Japanese troops invaded in 1592 Gakseong lead the Joseon troops in place of Seonsu who had been recommended earlier to the king by Samyeong Yujeong (四溟 惟政; 1544–1610). He launched a successful campaign against the Japanese navy during a battle at sea. Gakseong was once wrongly accused of a crime and subsequently imprisoned, but was released and given the title of Panseon'gyo Dochongseop 判禪教都摠攝. He was also appointed abbot of Bongeunsa, but resigned from that post soon after.

In 1624 he served as Paldo dochongseop 八道都摠攝 and directed the construction of the castle, Namhansanseong. He was able to complete the construction in 3 years for which he was rewarded with the title of Boeuncheongyowonjo Gugildo daeseonsa 報恩闡教圓照國一都大禪師. He spent the next few years repairing Hwaeomsa 華嚴寺 and teaching his disciples. He later taught at various temples such as Songgwangsa 松廣寺, Haeinsa 海印寺, Baeg'unsa 白雲寺, and Sangseonam 上仙庵, but returned to Hwaeomsa where he passed away on January 12th, 1660 at the age of 86.

He left many famous disciples such as Chwimi Sucho (翠微 守初; 1590–1668), Baekkok Cheoneung (白谷 處能; 1617–1680), Goun Jeongteuk 孤雲 挺特, Moun Jineon (慕雲 震言; 1622–1703), Dongnim Hyewon 東林 慧遠, Byeokcheon Jeonghyeon 碧川正玄, Chimheo Yulgye 枕虛律戒, Yeonhwa Inuk 蓮華印旭, Hoeeun Eungjun (晦隱 應俊; 1587–1672). Gakseongʼs lineage expanded into eight branches and his influence on the subsequent development of Korean Seon came to rival that of Cheongheo Hyujeong (淸虛 休靜; 1520–1604). He also wrote the Seonwonjip dojung gyeorui 禪源集圖中決疑, the Ganhwa gyeorui 看話決疑, and the Seongmun sangui cho 釋門喪儀抄.