Korea's greatest king was a bookish third son never meant to rule
As a boy, Yi To read so obsessively that his father reportedly confiscated his books to protect his health; he reread the one volume that was missed. Nobody expected this third son to reign. Yet as King Sejong he gave Korea its own alphabet, Hangul, and is widely ranked as its greatest monarch.
His father, King Taejong, had twelve sons and planned to hand over power while still alive to avoid a succession fight. The eldest, Grand Prince Yangnyong, was the designated heir but disobeyed, skipped his studies and chased women, and a scandal over an affair with an official's concubine in 1417 enraged the king. The studious younger brother, praised by the court and skilled in calligraphy, painting and the gayageum zither, became the obvious alternative. In mid-1418 Yangnyong was set aside, and within months Sejong was crowned.
Science flourished under him, often with his personal involvement. He revived the research body known as the Hall of Worthies in 1420, which produced the first native Korean calendar and a 365-volume medical compendium. When a solar eclipse in 1432 arrived two days after its predicted date, he ordered new astronomical instruments, leading to an armillary sphere and a water clock designed by Chang Yong-sil. In 1441 his son, the future King Munjong, led a team that invented a rain gauge, almost two centuries before Benedetto Castelli made one in Europe in 1639; gauges went out across the kingdom the following year.
Abroad, he launched a successful 1419 expedition against Tsushima Island that was followed by decades of peace and trade with Japan, pushed the northern frontier to roughly its present line and balanced loyalty to Ming China with Korean autonomy. At home, land and tax reforms raised harvests and lowered rates without much loss of revenue. He promoted Confucianism over Buddhism, even while privately practising Buddhism himself.
Chronic illness forced him to hand daily government to his son from 1445, and he died at 52 in 1450. South Korea honours him widely, including a city named after him. North Korean accounts praise his cultural work while stressing the heavy burdens peasants bore in his reign.
Source: Sejong the Great
