Treatise on Armament Technology, Volume 239

General Li Fangchun of the Left Army served alongside the Grand General of the Right Army, Ma Gui, under the direction of Commissioner Yang Hao. They set out from Chungju, crossing Choryeong Pass The text reads "Wuling" (烏領), likely a transcription error for the strategically vital Choryeong Pass (鳥嶺) toward Andong and hastening toward Gyeongju. Their primary objective was a concentrated attack on the forces of Katō Kiyomasa original: "Qingzheng" (清正), referring to the Japanese daimyo of the Second Division.

However, fearing that Konishi Yukinaga original: "Hangzhang" (行長), the Japanese commander of the First Division might lead reinforcements from the west, they ordered the Center Army to hold the Jeolla region to prevent him from being able to look elsewhere. They also detached over a thousand cavalry from the three armies to join the forces of Joseon Korea. This combined force descended through Cheonan, Jeonju, and Namwon.

Orders were given to the Pyongyang region to prepare 120,000 units of travel rations. They publicly proclaimed a massive offensive to unsettle the enemy's resolve and force them to divide their strength. Because the naval forces were few, they were ordered to remain in a hidden ambush; they were to wait for the battle to begin and then beat their drums to act as a decoy force Yibing (疑兵): literally "suspicion troops," a tactical unit used to make the enemy believe a larger force is present. If the Japanese fled in defeat, the naval and land forces would launch a pincer attack. After the generals swore their oaths, the army set out.

This occurred on the fourth day of the twelfth month of the Dingyou year Early January 1598. By the twentieth day, the troops converged at Gyeongju. They learned that the "enemy's nest" A common Ming term for a fortified enemy base was located at Ulsan. To the south of Ulsan lay Dosan. These two mountains were not particularly steep, but the Japanese had used the terrain to build a solid fortress. Between them flowed a river that provided a direct water route to Busan.