豐臣秀吉於1592年和1597年二次出兵朝鮮，諸將領中不少是教徒。這些將領的領地也是教徒眾多的地區，因此其軍隊中有入教士兵。日軍撤退至半島南海岸後，日、明雙方持續和談。由於歸國無期，士氣低落。篤信基督教的小西行長或許為鼓舞士氣，他向Gomez請求派遣傳教士至其軍中，因此西班牙傳教士Cespedes與日本人修士Leon同赴其駐守地熊川。Cespedes在熊川及機張，為軍中信徒講道、聽告解，安慰他們的心靈。也為新入教者洗禮，提供醫療服務等，但停留時間很短。日軍第二次入侵朝鮮時，亦有神父與修士短暫至半島。由於害怕異教徒告發，且朝鮮居民風聞日軍接近即逃走。因此，這些傳教士活動的地區既受限制，亦難與當地朝鮮人接觸。 日軍侵略朝鮮期間，隨軍僧侶有禪僧、日蓮僧、真宗僧、修驗僧等。他們與大明、朝鮮交涉和談、起草榜文、施藥醫療、從事戰鬥、弘法等。由於交涉和談均由小西行長與加藤清正主導，此兩軍軍中之僧侶因此成為雙方溝通的橋樑。隨軍僧侶在軍中之宗教活動記載甚少，但為戰死者祈冥福應是職責之一。 隨軍禪僧熟悉儒教，草擬之榜文即呈現儒家安民、恤民之統治理念。他們頌揚神功皇后征三韓，將兵端之起歸咎朝鮮。至於真宗僧，信仰熱忱、堅定，但著重現世利益。這些隨軍僧侶，無戰鬥時，多寄情詩賦，文人思維。

Toyotomi Hideyoshi 豐臣秀吉 launched invasions of Korea in 1592 and 1597. A number of generals were Christians whose territories also contained numerous Christians, and many of whose troops were Christian. After withdrawing to the south coast of the Korean peninsula, Japan continued peace talks with the Ming court. With no date for returning home in sight, morale among the troops was low. Being a devout believer, General Konishi Yukinaga 小西行長 turned for help to Pedro Gomez, vice-provincial of the Jesuit mission in Japan, requesting that a missionary be sent among the troops to boost morale. Gomez dispatched fellow Spanish missionary Gregorio Cespedes accompanied by a Japanese Jesuit brother Leon Fancan to the camp to preach, hear confessions, give pastoral care, carry out baptisms, and provide medical services to troops. However, their stay was short. During the second invasion of Korea, Christian missionaries and brothers were again sent to the peninsula for a short period, but feared accusations from followers of other faiths, and when Koreans living nearby got wind of the presence of the Japanese troops nearby, they fled. The area of missionary activity was therefore limited and contact with the local Koreans difficult. During the Japanese invasions of Korea, accompanying the troops were Zen禪, Nichiren日蓮, and Shinshuu真宗 monks. They communicated with representatives of the Ming and Korean courts, drafted announcements, provided medical services, participated in battles, and propagated Buddhist teachings. As the peace negotiations were led by Konishi Yukinaga and Katou Kiyomasa 加藤清正, the monks in their two armies became a bridge for communication. There are few records of their religious activities among the troops, but among their responsibilities was praying for the war dead. The Zen monks accompanying the troops knew much about Confucianism. The public notices they drafted incorporated ideas of Confucian government such as reassuring and showing concern for the people. They also praised Empress Consort Jingu's神功 attack on Korea in the Samhan三韓 period, blaming Korea for starting hostilities. Shinshuu monks were enthusiastic, firm believers, but stressed the interests of the present world. During breaks in the fighting, monks expressed their emotions in poetry and literary musings.