The "ship portrait" had a long history in maritime art, from medieval seals and coins to early engravings in the 15th century, and the plain side-on view of a ship under sail, often with no crew shown, was well established as the most effective way of recording the build of vessels.[6] The Anthony Roll belongs to a genre of works that was intended to serve a dual role for the king and the military leadership: as reasonably informative overviews listing details of ships or strategic areas of coastlines they could be studied to determine strengths and weaknesses, and as boastful and lively depictions of Tudor military might they could be used to flatter the king, impress courtiers and impose martial authority on foreign ambassadors. Contemporary maps, or "plats", were routinely decorated with detailed pictures of ships, to mark bodies of water as much as to liven up the scenes.