He was a Joseon dynasty official and became a righteous army leader during the Imjin war to repel the 1592 Japanese invasion of Korea.
Kim Chŏn-il, a middle-rank official who was then fifty-five years old, raised a small militia of three hundred men in his hometown of Naju.
He marched the militia north, recruiting along the way, intending to reach Uiju and defend King Seonjo from the invaders.
This city had successfully withstood a siege the previous year, and Kato wanted revenge for the setbacks Japan had suffered in the Imjin war.
Konishi Yukinaga informed Ming military advisor Shen Weijing of Kato's intent to attack, and told him that it was merely a face saving gesture rather than a new offensive.