[Lee Sang-hoon's Korean History] Kiyomasa Cornered by Allied Troops' Attack, Japan's Hero Overcoming Hardships

Battle of Ulsan Waeseong 'Half Success'

Sanghoon Lee, Professor of Military Science at the Korea Military Academy

The Battle of Ulsan Waeseong was a large-scale battle that took place from late December 1597 to early January 1598, near the end of the Imjin War. The “Joseon Expedition Folding Screen” housed at the Fukuoka City Museum in Kyushu, Japan, vividly depicts scenes from the Battle of Ulsan Waeseong. In Korea, it is known as the “Battle of Ulsan Fortress.” The artwork contrasts the large-scale Joseon-Ming allied forces besieging the fortress with the desperate Japanese soldiers inside, who were depicted eating horses.

Japanese records documenting the Battle of Ulsan Waeseong describe the Japanese troops suffering severe shortages of drinking water and food, resorting to drinking water mixed with blood, chewing paper, and boiling mud walls to survive. There are also accounts of them drinking the urine of those who had consumed water. Generally, it is known that Kat? Kiyomasa (加藤?正) endured one of the worst hardships during the battle, facing severe shortages of provisions and water. Kiyomasa, considered the most formidable Japanese warrior during the Imjin War, was surrounded by the Joseon-Ming allied forces in Ulsan and struggled to hold out.

After the Japanese army that initiated the Imjin War in 1592 was pushed back by reinforcements from Ming China and counterattacks by Joseon troops and militias, the front lines entered a lull, and the Japanese temporarily retreated southward. In 1597, Konishi Yukinaga (小西行長) fortified Waeseong in the west at Suncheon, while Kiyomasa built defenses in the east at Ulsan. Waeseong fortresses were mainly constructed on isolated hills 200 to 300 meters away from rivers or the sea, and the Japanese strategically placed about 30 such fortresses along the southeastern coast to strengthen their defense.

The Joseon-Ming allied forces decided to shift from defense to actively attacking Japanese strongholds. This sparked debate between attacking Yukinaga in Suncheon (Jeolla Province) or Kiyomasa in Ulsan (Gyeongsang Province). Ultimately, Ulsan Waeseong, close to the major Japanese bases of Busan and Seosaengpo and commanded by the prominent Japanese general Kiyomasa, was chosen as the first target.

Ulsan Waeseong is located today in Hakseong Park, Jung-gu, Ulsan. The fortress walls consist mainly of a stone-walled main enclosure (shukaku-bu) and an outer enclosure (gaikaku-bu) made of earthworks. The main enclosure was built in multiple layers of smaller enclosures (shokaku). At the summit of the hill, about 50 meters above sea level, was the Honmaru (本丸), with the Ninomaru (二之丸) positioned northwest at about 35 meters elevation, and the Sannomaru (三之丸) further northwest at about 25 meters elevation. To the south of the main enclosure, a dock was constructed to allow ships to dock at all times for transporting military supplies and troops.

The Battle of Ulsan Waeseong began on December 22, 1597, and lasted about ten days until January 4, 1598. The Joseon-Ming allied forces attacking Ulsan Waeseong numbered approximately 40,000. The left wing attacked the enemy camp at Bangujeong (伴鷗亭), the center force advanced directly along Byeongyeong-gil to assault the main camp, and the right wing surrounded enemy positions along the Taehwa River. Ming guerrilla commander Mao Guoqi (茅國器) led elite troops from Zhejiang to break through the outer defenses, and guerrilla commander Chen Yin (陳寅) also breached the outer fortifications. Eventually, the Japanese abandoned all outer positions and retreated to the main enclosure of Ulsan Waeseong.

Unlike the outer defenses, Ulsan Waeseong’s main enclosure was sturdy. After several failed assaults, the Joseon-Ming allied forces withdrew and laid siege to isolate the fortress. They filled in wells around the fortress and cut off supply routes. The Japanese trapped inside suffered from cold, shortages of water and food, and faced near annihilation due to depletion of ammunition and supplies.

The “Art of War” (Sun Tzu), in the chapter on strategic attack (Mougong Pian, 謀攻篇), states: “If your forces are ten times the enemy’s, surround them; if five times, attack them; if twice, divide them.” The construction of Ulsan Waeseong was overseen by Ota Kazuyoshi (太田一吉), with about 16,400 Japanese personnel involved. They dismantled nearby town and military fortresses to reuse the stones for the fortress. Since most of the laborers were Japanese troops, this number roughly represents the total Japanese garrison. Thus, the battle was between about 40,000 Joseon-Ming allied troops and approximately 16,400 Japanese defenders.

The allied forces outnumbered the Japanese by about 2.5 times. While they had numerical superiority, it was not an overwhelmingly large margin for a siege. Moreover, the allied forces were a coalition of Joseon and Ming troops, lacking a unified command structure and facing communication difficulties. Although the allied morale may have surpassed that of the Japanese, the Japanese were more skilled with short weapons. The allied forces had to conduct siege warfare against a fortress on a hill, but they lacked adequate siege weapons and could not effectively use artillery due to the terrain. The siege of Ulsan Waeseong was not an easy operation from the start.

“On December 26, with grain and water running out, it was inevitable that people would start dying. Already, one or two have collapsed and died. Inside this fortress, the hardships are limited to three things: cold, hunger, and thirst.”

Keinen (慶念), a monk from Any?ji Temple (安養寺) in Oita Prefecture, Kyushu, served as a military doctor during the Jeongyu War and wrote the “Joseon Daily Diary” (朝鮮日日記). The above entry is from December 26, four days after the battle began, indicating the severe cold, food shortages, and water scarcity experienced by the Japanese inside the besieged fortress.

However, Keinen’s diary entry on December 22 states, “Around breakfast, their (the allied forces’) attack intensified.” Although besieged, the Japanese were still able to have proper meals early in the battle. On December 25, Keinen noted, “Heavy rain fell, allowing everyone to quench their thirst,” and on December 28, he wrote, “Water and food supplies further decreased, making everything difficult and distressing.” This suggests that on December 26, supplies were not yet completely exhausted. The deaths of one or two people on that day were likely due to battle fatigue or illness rather than starvation or dehydration.

As time passes, the situation for those under siege naturally worsens. However, Keinen’s diary does not mention shortages of food or water after December 28, nor are there records of deaths caused by such shortages. The Japanese had stockpiled large quantities of military supplies in advance when constructing Ulsan Waeseong. While the besieged Japanese certainly faced difficulties with water and food, the situation was not as dire as often assumed.

The siege of Ulsan Waeseong lasted from December 23 to January 4 of the following year. The “Jingbirok” records, “When the enemy troops reached the foot of the fortress, bullets rained down like a storm,” and the “Annals of King Seonjo” note that on December 25, 26, and 29, enemy gunfire was as heavy as rain. The Japanese continued to fire arquebuses relentlessly until the allied forces withdrew on January 4. In the final assault, about 500 Ming soldiers were hit by Japanese gunfire. The Japanese garrison at Ulsan Waeseong did not run out of ammunition until the siege ended.

After the Imjin War, Japan sought to reassess the conflict through military chronicles. Among them, the “Yoshikawa Family Treasure” (吉川家寶) states, “The Japanese at Ulsan Waeseong numbered only 20,000, while the Joseon-Ming allied forces exceeded one million.” This exaggeration emphasizes how Kiyomasa’s forces, though vastly outnumbered by the “million-strong” allied army, did not surrender and miraculously survived. It dramatizes Kiyomasa’s heroic story and glorifies the Japanese military.

If the Joseon-Ming allied forces had pressed their early advantage and maintained an aggressive offensive, they might have inflicted significant damage. Had they accepted the risks and continued the assault, they might have captured Ulsan Waeseong and taken Kiyomasa prisoner. Japan highlights overcoming extreme adversity in the Battle of Ulsan Waeseong to glorify itself, while Joseon takes solace in having pushed Kiyomasa into a desperate situation. Ultimately, the differing perspectives of Japan and Joseon have distorted the image of the Battle of Ulsan Waeseong.

Lee Sang-hoon, Professor of Military Studies, Korea Military Academy