Database: Sea Warriors & Military Boats

In medieval Japan, "sea warriors" had their own territories on the sea. There was a different enforcement structure on the waves, the warriors collected tolls from ships sailing in their waters and attacked those who did not pay. Essentially, they were pirates. In the 16th century, the terrestrial lords developed closer relationships with these "sea warriors," integrating them into their vassalage to secure cooperation due to the necessity of sea transport and naval battles with other lords. Famous examples are the Mōri and the Murakami of the Inland Sea (Seto-naikai), as well as Oda Nobunaga and the Kuki of Shima Province: two naval forces that battled in Osaka Bay during the Hongan-ji war.

Toyotomi Hideyoshi appointed his trusted subordinates as feudal lords in Awaji province (on the eastern edge of the Inland Sea) and asked them to mobilize the "sea warriors" in their territories, which was essential for the invasions of Kyushu, Kantō, and later, Korea. The ships used in Japan at that time were basically coastal or river boats, with flat bottoms and no keel. There were three main categories of boats: the large, heavily defended warships called atakebune; the fast, medium-sized sekibune boats; and the small kohayabune, used for reconnaissance or communication. During the Hongan-ji war, Nobunaga is said to have built an iron-plate covered atakebune.