He was a notable general during the Seondeok era. In 636, he obeyed the order of the queen and marched to Yeoguen-gok (女根谷) and then repulsed the Baekje forces. In 638, Goguryeo forces invaded Chiljung castle (today's Paju). Alcheon led his soldiers to victory over the Goguryeo forces.
In 654, Queen Jindeok died without a successor, Alcheon became the favorite to take the throne of Silla. However, Alcheon refused to take the crown and, along with Kim Yushin, supported Kim Chunchu. As a result, Kim Chunchu ascended the throne.
- ^ Il-yeon: Samguk Yusa: Legends and History of the Three Kingdoms of Ancient Korea, translated by Tae-Hung Ha and Grafton K. Mintz. Book One, page 64. Silk Pagoda (2006). ISBN 1-59654-348-5