Rason Alliance

Overview

The Rason Alliance (羅濟同盟) was an alliance between Silla and Baekje formed to resist the southward expansion of Goguryeo. Broadly, it includes the rapprochement between Geunchogo of Baekje and Naemul of Silla in the 4th century, but usually it refers to the so-called second alliance concluded in 433 between King Biyu of Baekje and King Nulji of Silla. It was a military alliance of mutual assistance (攻守同盟) in which each side sent reinforcements when needed; it lasted nearly 120 years before collapsing in 553 with Silla's occupation of the lower Han River basin.

Background

In 366, Geunchogo of Baekje sent an envoy to Naemul of Silla to establish friendly relations. However, toward the end of Naemul's reign Silla drew closer to Goguryeo again, and this relationship broke down. Baekje, together with Wa and Gaya, attacked Silla, and Silla received aid from Goguryeo (Gwanggaeto the Great's Relief of Silla). Afterward, Silla came under the stationing of Goguryeo troops and interference in its domestic affairs.

When the southward advance of Goguryeo became full-scale with King Jangsu's relocation of the capital to Pyongyang in 427, both Baekje and Silla felt threatened. Baekje approached the Northern Wei but achieved no results, while its negotiations with Silla, which sought to escape Goguryeo's interference, succeeded.

Course of Events

• 433 King Biyu of Baekje sent an envoy to Silla requesting friendly relations, and King Nulji accepted.
• 455 When Goguryeo attacked Baekje, Silla sent troops to aid Baekje.
• 475 When King Jangsu of Goguryeo attacked Hanseong, King Gaero sent his son Munju to Silla to request aid, and Silla sent 10,000 men. However, Hanseong fell before the reinforcements arrived (Fall of Hanseong of Baekje). Munju returned with Silla's troops, ascended the throne, and moved the capital to Ungjin.
• 493 King Dongseong of Baekje took as his wife the daughter of Biji, Ichan of Silla, strengthening the alliance through marriage.
• 551 King Seong of Baekje, allied with Silla and Gaya, attacked Goguryeo and recovered six commanderies in the lower Han River basin, while Silla took ten commanderies in the upper Han River basin (Silla's Acquisition of the Han River Basin).

Outcome