The Yi Dynasty Korea, which had been Sakuho-koku (countries to confer a peerage with a Saku paper) of Ming, did not have the intention of leading troops to conquer Ming and Hideyoshi decided to conquer Korea at first in order to make a successful expedition to Ming and a large army of 160,000 were sent in May 1592 (according to the traditional Japanese calendar).
明の冊封国であった李氏朝鮮に征明嚮導の意思はなく、秀吉は明への遠征のため先ず朝鮮の制圧を決め、文禄元年（1592年）4月（和暦。漢数字表記の月は以下同じ）、16万人の大軍を送ることとなる。