Battle of Sacheon (1598)

The 1598 battle of Sacheon (泗川) was a siege by Korean and Chinese forces against the Japanese fortification of Sacheon on September 28-29, 1598, during Toyotomi Hideyoshi's invasions of Korea. The Japanese were able to withstand the siege, and due to a fortuitous explosion in the Chinese artillery unit's powder magazine, attacked and drove off the Chinese and Korean army. There are conflicting accounts of how many men participated and how many were killed, but all accounts agree that the Japanese garrison was heavily outnumbered and emerged victorious.

Background
Sacheon is a natural harbor located on the southern coast of Korea, in what was then called Jeolla province. Shimazu Yoshihiro and his son Tadatsune came to Sacheon in 1597 after aiding in the Japanese capture of the fortress of Namwōn. There, they built a new Japanese-style castle directly on top of the old Silla fort, and shortly afterwards another, larger castle right at the port, about six kilometers to the south. By 1598, this new castle contained an inner wall around the keep, surrounded by a natural moat which filled with sea water during high tide only, allowing ships to enter the moat. The outer wall encompassed a much larger area with additional guntowers and several fortified gates.

As with many battles during the Imjin war, the three accounts (Chinese / Korean / Japanese) vary wildly in the deciding factor for the outcome of the battle, and more importantly in headcount, regarding both men deployed and lost. Some Japanese sources claim that the Ming army had up to 200,000 soldiers, which was nearly triple the number of the total men the Ming sources said they deployed in the entire Korean campaign. The Ming sources said they had a combined strength of 30,000 at the siege, yet the Japanese source most widely cited claimed 37,000 heads were taken. Korean sources said the allies lost about 7 to 8 thousand men.

Siege
Koreans and their Ming Chinese allies began pushing south in 1598, reclaiming territory lost to the Japanese in the battles of the preceding years. By September, an army of 34,000 Chinese warriors under the command of Dong Yiyuan 董一元, along with 2000 Korean warriors, was ready to lay siege to the newer, larger Sacheon castle. Murakami Tadazane, commander of the smaller garrison, brought his 300 men to the larger castle, joining up with Shimazu Yoshihiro's force of 8,000, before the Chinese/Korean force began their assault on October 1.

The allied forces began their assault at midnight on September 28. The old castle fell quickly at about 3:00 a.m. on the next day, and the Japanese split their force in three, retreated and sallied forth from the new castle's three gates. A big fire suddenly appeared at the rear of the besiegers and sent them into chaos. The Japanese stormed forth and defeated them. According to the chronicle of the Shimazu clan, 37,000 heads were taken; and still numerous dead bodies were left on the battle field. A hole was dug, twenty ken across (about 36 meters), to bury the bodies.

Chinese contemporary sources such as Dong Yiyuan's biography in the official history of Ming (忽營中砲裂，煙焰漲天. 賊乘勢衝擊，固城援賊亦至)and (諸葛元聲《兩朝平壤錄)(The two trips to Pyongyang by Zhuge Yuansheng) wrote that the cause of the defeat was a serious artillery explosion that triggered a massive chain explosion of the entire Ming army gunpowder cache, which sent the army into complete disarray, and the Japanese took advantage of the moment and sallied forth. The artillery division, some 3000 men from Zhejiang province, suffered the highest casualties, only about 50 men reported back to the army after the dust had settled.