Kim Sammaekjong (526–576; reign 540–576) was the 24th monarch of Silla, one of the Three Kingdoms of Korea. He followed King Beopheung (r. 514–540) and was followed by King Jinji (r. 576–579). Jinheung was the nephew / grandson of King Beopheung. King Jinheung was one of the greatest kings of Silla, and was responsible for expanding Silla territory immensely. He and King Seong 26th king of Baekje, struggled with each other over the Han River valley. Jinheung won this struggle and expanded Silla's territory immensely. Rise to the throne King Jinheung of Silla rose to the throne at a young age when his predecessor and paternal uncle / maternal grandfather, Beopheung, died. Since he was too young to rule a kingdom at the time, his mother Queen Jiso acted as regent. When he became of age, he began to rule independently. One of his first acts as true king of Silla was to appoint a man named Kim Isabu as Head of Military Affairs, which occurred in 541. Jinheung adopted a policy of peace with the neighbouring kingdom of Baekje Kingdom. In 551, he allied with Baekje so that he could attack the northern Korean kingdom of Goguryeo. The result of this allied attack on Goguryeo was the conquest of the Han river estuary. The kingdoms of Baekje and Silla agreed on splitting the conquered territory equally between themselves. Expansion During the reign of King Seong of Baekje, King Jinheung allied with Goguryeo and launched an attack on the Han River valley during the year 553. In a secret agreement between Silla and Goguryeo, Silla troops attacked the exhausted Baekje army in late 553. Feeling the betrayal from Silla, King Seong attacked during the year 554, but was caught in an ambush led by a Silla general and was assassinated along with those who were accompanying him. King Jinheung guarded the new territory with a firm hand for seven years before sending General Kim Isabu to conquer Daegaya in 561. King Jinheung constructed a monument in his newly conquered territory and established provinces in the area. He subdued all rebellions and continued to develop culture in his kingdom. In 576, the Hwarang was established, and they would later play a huge role in the unification of the Three Kingdoms of Korea. Death and succession King Jinheung died in 576 at the age of 51. His 37-year rule of Silla was