[citation needed] In 636, Alcheon, who was then a general, received orders from Queen Seondeok to drive off the Baekje forces in Yeoguen-gok.
[6] In early 638, Alcheon repelled invading Goguryeo forces outside Chiljungseong Fortress [ko], capturing and killing numerous enemy soldiers.
[6] Despite his victories against both Baekje and Goguryeo forces, no records of his career as the Grand General of Silla after the 638 battle of Chiljungseong Fortress appear in historical sources.
[2] With no Seonggol heirs to inherit the throne, the Hwabaek Council offered Alcheon the position of king regent by procedure.
[2] However, Alcheon declined the offer on account of his "old age" and "lack of virtue";[10] he instead endorsed Kim Ch'un-ch'u, who would later assume the throne as King Muyeol of Silla.