"The struggle for dominance during the Warring States period did not take place exclusively on land, since naval forces were necessary to extract wealth from international trade, to transport and protect the movement of armies by water, and to defend coastal populations from raiding. Rather than develop their own navies, land-based warlords hired groups possessing the necessary skills and equipment, entering into uncomfortably tenuous patronage relationships with them. These groups were often referred to as 'pirates,' depending upon whom they were working for and who was describing their actions, but Peter Shapinsky's work presents these sea lords in similar terms to land-based warlords, but functioning in a different ecological niche. They played critical roles in several important battles, but remained fluid in their loyalties."
* Turnbull ill. Hook 2007 p20
"[D]omestic piracy continued within Japan under the auspices of the 16th-century version of the kaizoku. In much the same way that landlocked daimyo established their territories by the thoroughly respectable business of stealing land and building castles on it, so the more astute families of Kyushu and the Inland Sea entered the new Japanese aristocracy through naval warfare.
"Just as in the days of Fujiwara Sumitomo, the numerous islands and inlets of the Inland Sea provided excellent pirates' lairs. The most famous family associated with the 'pirate kings' was Murakami, of whom there were three active branches based on the islands of Noshima, Kurushima and Innoshima. Several daimyo courted their services, because only the most completely landlocked warlord felt that he could do without a navy."
* Turnbull ill. Hook 2007 p30-31
"The kaizoku who operated in the Inland Sea during the 16th century would have been more substantially dressed and armed than those who raided China and Korea. Short voyages and friendly ports meant that heavier weapons and armour could be used, and when a daimyo sent a fleet against his enemies there was every chance that his opponents would be equipped with the latest weaponry, so measures were taken accordingly. One authority recommends that for fighting in a boat, the samurai should wear only a do (body armour) and helmet, discarding facemask, sleeves, shinguards and thighguards. The identifying sashimono (back flag) would also be inconvenient, so this should be replaced with a small sode-jirushi (shoulder-flag).
"A ship's commander would have worn an elaborate suit of armour, but for the ordinary sailors the simple okegawa-do-style of suit of armour as worn on land by the ashigaru (footsoldiers) provided good protection for the most vulnerable parts of the body. It consisted of a small number of armour plates riveted together and lacquered over to give a smooth surface. A row of skirt pieces hung down around the groin and upper thigh. It would be worn over a simple shirt and trousers, leaving bare arms and bare feet in straw sandals. In hot weather at sea the shirt might be omitted."