Kiyomasa hunting a tiger in Korea. Tiger hunting was a common pastime for the samurai during the war.
During the Seven-Year War
Kiyomasa was one of the three senior commanders during the Seven-Year War (1592¨C1598) against the Korean dynasty of Joseon. Together with Konishi Yukinaga, he captured Seoul, Busan and many other cities. He defeated the last of the Korean regulars at the Battle of Imjin River and pacified Hamgyong.
Kiyomasa was an excellent architect of castles and fortification. During the Imjin war, he built several Japanese style castles in Korea to better defend the conquered lands. Ulsan castle was one of the fortresses that Kiyomasa built, and it proved its worth when Sino-Korean forces attacked it with a far superior force, yet the outnumbered Japanese were able to successfully defend the castle until reinforcements arrived, which forced the Sino-Korean force to retreat.
The Korean king Seonjo abandoned Seoul before Kiyomasa's forces. Kiyomasa held two Korean princes who had deserted as hostages and used them to force lower-ranking Korean officials to surrender. During the war, he apparently hunted tigers for sport, using a spear, and later presented the pelts to Hideyoshi. Kiyomasa's most famous battle is the Siege of Ulsan on December 22, 1593. Kiyomasa led the defense of the castle, successfully holding Chinese general Yang Hao's army at bay, which numbered 60,000. He defended Ulsan until November 23, 1598. However, his bravery was not reported to Hideyoshi by his rival's overseer Ishida Mitsunari. After Hideyoshi's death, he clashed with Mitsunari, and approached Tokugawa Ieyasu.
William Scott Wilson describes Kato Kiyomasa thus: "He was a military man first and last, outlawing even the recitation of poetry, putting the martial arts above all else. His precepts show the single-mindedness and Spartan attitudes of the man, [they] demonstrate emphatically that the warrior's first duty in the early 17th century was simply to 'grasp the sword and die'. Contemporary accounts of Kato describe him as awe-inspiring, yet not unfriendly, and a natural leader of men."