Sejong the Great, also known as Yi Do, became the fourth monarch of the Joseon dynasty in Korea. He is highly regarded in Korean history and is famous for inventing Hangul, the native alphabet of the Korean language.

Sejong the Great became the king of Korea during the Choson Kingdom in 1397. He was a progressive and scholarly leader who promoted literacy and developed a new form of writing to enhance communication among Koreans.

King Sejong the Great started his rule over Korea as the fourth king of the Joseon Dynasty in 1418. His reign had a significant impact on Korea and its people.

In 1404, Sejong's eldest brother Yi Je was named heir apparent by King Taejong. However, Yi Je's demotion in 1418 led to Sejong's eventual ascension to the throne.

At the age of 12, Sejong was named Grand Prince Chungnyeong by his father, King Taejong.

Crown Prince Yi Hyang, the first son of Sejong the Great, was born on October 3, 1414. He later became King Munjong of Joseon and ruled from 1450 to 1452.

Yi Yu, also known as Grand Prince Suyang and the second son of Sejong the Great, was born on September 29, 1417. He played a significant role in Korean history and later became King Sejo of Joseon.

In June 1418, Sejong's older brother Yi Je was removed from the position of heir apparent due to his free spirited nature and preference for hunting and leisure activities. This led to Sejong's quick ascension to the position.

In August 1418, Taejong abdicated the throne in favor of his youngest son, Sejong the Great, securing his position as heir apparent.

In September 1418, Taejong abdicated the throne, paving the way for Sejong the Great to become king. Taejong continued to influence government policy even after his retirement.

In May 1419, King Sejong dispatched the Gihae Eastern Expedition to confront Japanese pirates operating off Korea's east coast. The military force successfully defeated the pirates, rescuing Chinese and Korean captives.

Sejong the Great founded the Hall of Worthies (Jiphyeonjeon) in 1420, serving as advisors to the king and a center for academic research.

Sejong the Great's ascension to the throne was unique as he became king after his father's abdication in 1422. His surprising political skill and creativity became apparent after his father's death.

King Sejong attempted to balance the state ideology of Neo-Confucianism with a tolerance for Buddhism in nonofficial contexts, reflecting his personal belief in Buddhism while managing the political demands of his time.

In 1426, King Sejong enacted a law granting government slaves women 100 days of maternity leave after childbirth, which was later extended by one month in 1430.

In 1429, King Sejong published the Nongsa Jikseol, a comprehensive guide on farming techniques including planting, harvesting, and soil treatment. The handbook aimed to support farmers in adopting intensive cultivation methods.

In 1430, King Sejong initiated a nationwide public opinion poll to gather feedback on a new tax system called Gongbeop, with approximately 57% of the 172,806 respondents approving the proposed reform.

In 1433, King Sejong sent General Kim Jong-seo to the north to defeat the Jurchens, later known as the Manchus. Kim's campaign led to the capture of several fortresses and the expansion of Korean territory to the Songhua River, establishing forts and posts for protection.

In 1439, Sejong the Great's health started deteriorating, and his eldest son, Crown Prince Yi Hyang, took on the role of regent. This marked a period of transition in the leadership of Korea.

During the reign of King Sejong in 1440, Korean cartographers updated the maps of Korea with new inventions and astronomical observations. They moved the prime meridian to Seoul, enhancing the accuracy of Korean maps compared to those of Chinese capitals.

During the Sejong era in 1442, Jang Yeong-Sil, a peasant with remarkable scientific ability, invented a precise water clock. Recognizing his talent, King Sejong brought him to court to work on inventions.

King Sejong of Joseon introduced Hangul, the Korean alphabet, to improve literacy among the common people. This new writing system was designed to be easy to learn and use, allowing even peasants to become literate in a short period of time.

During his reign, King Sejong instructed his scientists to compile the Nongsa Jikseol, an agricultural book containing information on materials and best practices from all regions of Korea. The book aimed to help Korean farmers improve crop yield.

Queen Soheon, the consort of Sejong the Great, passed away on March 24, 1446. She was known for her influence on Sejong and her support for the development of Hangul.

King Sejong the Great passed away in 1450 after ruling Korea for over three decades. His legacy and contributions continued to influence Korea and Koreans.

After the death of King Munjong, his young grandson Danjong became the king of Joseon. However, political stability deteriorated and Sejong's second son, Grand Prince Suyang, seized the throne in 1455 by overthrowing Danjong.

Tsushima remained a territory of the Joseon Dynasty until 1951, when the claim was relinquished. This prolonged period of control had lasting implications on the region.

The South Korean Navy launched the first King Sejong the Great class of guided missile destroyers in 2007, named in honor of King Sejong the Great. These destroyers are a testament to the king's military legacy.

In 2008, the Korean television drama series Daewang Sejong, also known as 'King Sejong the Great,' was released. The series focuses on the life and achievements of King Sejong the Great, with actor Kim Sang-kyung portraying the king.

A 9.5-meter-high bronze statue of King Sejong was erected in Gwanghwamun Square, Seoul, along with the opening of the underground museum exhibit 'The Story of King Sejong' on Hangul Day, commemorating the 563rd anniversary of the Korean alphabet's invention.

Sejong the Great was a monarch of the Joseon Dynasty in Korea known for his contributions to Korean culture and technology, including the creation of the Korean alphabet, Hangul.