Prompted by King Seonjo, the Buddhist monk Hyujeong issued a manifesto calling upon all monks to take up arms, writing "Alas, the way of heaven is no more. The destiny of the land is on the decline. In defiance of heaven and reason, the cruel foe had the temerity to cross the sea aboard a thousand ships". Hyujeong called the samurai "poisonous devils" who were "as virulent as snakes or fierce animals" whose brutality justified abandoning the pacifism of Buddhism to protect the weak and innocent. Hyujeong ended his appeal with a call for monks who were able-bodied to "put on the armor of mercy of Bodhisattvas, hold in hand the treasured sword to fell the devil, wield the lightning bolt of the Eight Deities and come forward!". At least 8,000 monks responded to Hyujeong's call, some out of a sense of Korean patriotism and others motivated by a desire to improve the status of Buddhism, which suffered discrimination from a Sinophile court intent upon promoting Confucianism.

Hyujeong and the monk Yeonggyu gathered a force of 2,600 to attack Cheongju, which served as the administrative center of central Korea and contained a large government granary. It was previously taken on 4 June and was under the control of Hachisuka Iemasa.

When the Koreans attacked, some of the Japanese were still out foraging for food. The Japanese came out and fired at the Koreans, but they were surrounded and killed. The Koreans didn't know how to use the matchlock firearms, so they used them as clubs. At this point a heavy downpour started so the Koreans fell back and retreated. The next day the Koreans discovered the Japanese had evacuated from Cheongju and took the city without a fight.