Seonjo (Korean: 선조; Hanja: 宣祖; 6 December 1552 – 6 March 1608), personal name Yi Yeon (이연; 李昖), was the 14th monarch of the Joseon dynasty of Korea.

Yi I, a neutral conservative, urged the king to increase the size of the army to prepare against future invasions from the Jurchens and Japanese.

The Jurchens and Japanese used this opportunity to expand their influence in East Asia, resulting in the Seven-Year War, and the foundation of the Qing dynasty in China, both of which would lead to devastation on the Korean Peninsula.

[4] King Seonjo faced many difficulties dealing with both new threats, sending many skilled military commanders to the northern front, while contending with Japanese leaders Oda Nobunaga, Toyotomi Hideyoshi and Tokugawa Ieyasu in the south.

He also ordered the construction of many forts in the coastal regions and sent generals Sin Rip and Yi Il to the southern coast to prepare for war.

While the Koreans were busy making their preparations, the Japanese manufactured muskets for many of their soldiers, mobilized warriors from across the entire country.

Yi Il met up with General Sin Rip and engaged Konishi's troops at the Battle of Chungju, but were defeated.

Then Seonjo appointed General Kim Myeong-won as Commander-in-Chief and Field Marshal, and ordered him to defend the capital and moved to Pyongyang as the Japanese began encroaching upon the city.

While the king was absent from the capital, many people who had lost hope in the government plundered the palace and burned many public buildings, including the Gyeongbokgung.

[9][10][11] During Seonjo's stay at Uiju, he wrote the Joseon government's first public document written solely in Hangul, rather than Hanja.

[12] Although the army continued to lose men and battles, the navy under Admiral Yi Sun-sin defeated the Japanese fleet several times and did much damage to the supply ships.

With the navy blocking supplies, Ming forces arrived at the request of Seonjo and began to push the Japanese southward, eventually retaking Pyongyang.

A month before he returned to Hanyang, Seonjo wrote an edict in Hangeul where anyone that either captured Japanese forces in battle, reported on invading troop movements, or rescued Korean prisoners would receive the title of government official regardless of class.

The ensuing Battle of Noryang marked the end of the war, with the last Japanese units under Konishi Yukinaga leaving Korea.

However, when the queen gave birth to Grand Prince Yeongchang (Gwanghaegun was the second son of Lady Kim, the king's concubine), the succession also became a matter of contention.