Goguryeo–Yamato War

The Goguryeo–Yamato War occurred at the end of 4th century and the beginning of the 5th century between Goguryeo and Yamato era Japan. After this war, Goguryeo made both Silla and Baekje its subjects, bringing about a loose unification of Korean Peninsula that lasted about 50 years.

Timeline

 * In 396, Gwanggaeto the Great led troops and conquered many Baekje castles. As the troops reached the capital, King Asin of Baekje surrendered and swore to be a subject of Goguryeo. Gwanggaetto returned home with a kidnapped Baekje prince and some nobles.
 * In 399, Baekje broke a previous promise and allied with Wa. Gwanggaeto advanced to Pyongyang. There he saw Silla's messenger who told him that Baekje and Wa's troops were crossing the border for invasion, and asked Goguryeo for help. As Silla swore to be Goguryeo's subject, the king agreed to save them.
 * In 400, Gwanggaeto the Great sent 50,000 troops to save Silla. Wa's troops retreated to Gaya before the Goguryeo troops reached the Silla capital. Goguryeo and Silla alliance pursued to Wa's forces at the castle in Alla. The troops in the castle soon surrendered.
 * In 404, Yamato unexpectedly invaded the southern border at former Daifang territory. The king led troops from Pyongyang to prevail. The Yamato troops lost the battle against Goguryeo in the vicinity of Pyongyang.