Hideyoshi's last major ambition was to conquer the Ming dynasty of China. In April 1592, after having been refused safe passage through Korea, Hideyoshi sent an army of 200,000 to invade and pass through Korea by force. During the Japanese invasions of Korea (1592–1598), the Japanese occupied Seoul by May 1592, and within three months of the invasion, the Japanese reached Pyongyang. King Seonjo of Joseon fled, and two Korean princes were captured by Katō Kiyomasa. Seonjo dispatched an emissary to the Ming court, asking urgently for military assistance. The Chinese emperor sent admiral Chen Lin and commander Li Rusong to aid the Koreans. Commander Li pushed the Japanese out of the northern part of the Korean Peninsula. The Japanese were forced to withdraw as far as the southern part of the Korean peninsula by January 1593, and counterattacked Li Rusong. This combat reached a stalemate, and Japan and China eventually entered peace talks.