"The atakabune-class naval ship was used during Japan’s warring states period of the sixteenth century, when rival daimyo built fleets to occasionally engage in naval warfare. When Toyotomi Hideyoshi unified the country’s disparate clans under his leadership, he also gained control of many feudal armies. The invasion of Korea in 1591 saw the redeployment of many weapons Toyotomi had acquired from his former enemies, including the atakabune-class ships. They proved vital in the invasion, as well as in the subsequent campaigns lasting until 1598.
The atakabune was a boxy, armored ship by design, its hull held together with iron nails that were highly susceptible to rusting. As a result, the atakabune was not suited for carrying heavier payloads, like cannons. The preferred method of Japanese naval combat consisted of grappling an enemy vessel and then boarding with an assault party, so the lack of cannons was not a hindrance."