Shugo daimyo (shugo, which were Japanese provincial military governors, that became daimyo, which were Japanese feudal lords) organized kaizoku shu on their periphery into keigo shu and used them as their naval military force in exchange for providing them the land in their territory under the pretext to guard the land.
守護大名は周辺の海賊衆を、領内の田畑を警固料の名目で所領として給する代償に警固衆に編成、海上軍事力に利用した。