 In 553, Baekje gained the critical region after expending itself with a series of costly assaults on Goguryeo fortresses, but Silla troops, arriving on the pretense of offering assistance, attacked the exhausted Baekje troops and took possession of the entire Han River region, leading to a war between the two former allies in which the Baekje monarch was killed.Baekje attacked Silla in 612, 624, and 627.Goguryeo and Baekje formed an alliance (Hangul