Several groups of monks, organized around various abbots & leaders who took the roles of generals and commanders, fought off the Hideyoshi invasion on various fronts. Their principle weapons are recorded as being spears & sickles. The primary general was Seosan-daesa (The Great Monk, Western Mountain). After the armies of Choson were crushed by the Japanese, a monk named Yong-gyu took his musaeng (warrior monks) to fight the Japanese at Cheongju. Yong-gyu was Seosan-daesa's disciple. Yong-gyu was victorious at Cheongju, but lost his life at Keomsan.
The King asked Seosan-daesa to come out of seclusion in order to save Choson. The 73 year old monk became the leader of the Monks' Army. Seosan-daesa raised units of warrior monks from monasteries across Korea, his own company numbering 1,500 strong. In particular was another of Seosan-daesa's disciples, Samyungdang, who's own unit was made up of 800 fighters. Other monks joined with militia units of their own, bringing the number of the warrior monk army to 5,000. With the help of reinforcements from the Ming army, they liberated Pyongyang. Continuing on from there, Samyungdang drove the remaining Japanese out of the southeast. When the Japanese invaded again in 1597, Samyungdang raised an army of 1,000 monks and attacked Kato Kiyomasa's base. He himself led infiltration teams (the real Korean ninjers) into Kiyomasa's camp to gather intelligence, and used this information to sue for peace talks. During one of these talks, he came face to face with Kato Kiyomasa. In an act of defiance that even the Japanese came to revere, Samyungdang told Kato Kiyomasa that the Choson Dynasty's crown jewel was Kiyomasa's head, and that the people of Choson would only know peace if he cut that head off.
Samyungdang was later asked by the King to pursue peace talks in Japan, where he was greeted by the Japanese with reverence for his bravery. The talks were successful and Samyungdang returned to Korea with around 3,000 POWs.
It is important to note that most of these monk-generals are not revered only for helping defend the nation from the Japanese, but that all of them, particularly Seosan & Samyung, are respected for their contributions to Korean Buddhism and practice.