An original letter from Toyotomi Hideyoshi to his retainer Katō Kiyomasa has been found in Japan. In the document, which bears Hideyoshi’s personal seal under the date of 23rd day of the 3rd month of the lunar calendar, Hideyoshi orders Kiyomasa to invade Korea. The invasion took place in 1592. For further details read the Asahi Shimbun article here.
