At age twelve Sejong excelled various studies and was favoured by the king Taejong (father). His older brother believed Sejong was destined to become king in his belief he acted rude to the court and was kicked out. Him getting kicked out brought Sejong to the throne. The eldest became a traveler and lived in the mountains while the second son became a monk.
Sejong ascended the throne in 1418. But Taejong still had some powers at court particularly regarding military matters-until his death in 1422.
STRENGHENING OF THE KOREAN MILITARY
Sejong was a very good military planner because of his effectiveness. A lot of the military regulations he created were to protect and strengthen the safety of his kingdom. He helped Korea advance in the canon development, military technology, different kinds of mortars and fire arrows that were tested as well as gunpowder.
In May 1419, king Sejong, with the guidance and advice of his father, embarked on the Gihae eastern expedition: his goal was to get rid of the Japanese pirates who had been operating out of Tsushima Island. On his expedition 243 Japanese were killed, 110 captured in combat and 180 Korean were killed. 146 Chinese and 8 Koreans were liberated in the expedition. The daimyo’s of Tsushima and Sadamori capitulated to the Joseon court in September 1419. In 1443 the treaty of Gyehae was signed. The Joseon court rewarded the Sō clan preferential rights regarding trade between Japan and Korea because daimyo of Tsushima obeyed the suzerainty of king Joseon. Sejong sent Kim jong seo , a general from north, to kill the machu. The military campaign of Kim captured several castles, pushed north and restored the Korean territory (which is now the present day border between china and North Korea.
Science and technology
Sejong was (is) loved for his technological advances during his reign. He helped farmers by giving them a handbook, the handbook was filled with techniques gathered from different regions in