Most of the Duchy's possessions in Thessaly were lost when the region was conquered by the Serbs of Stefan Dushan in 1348, but Neopatras and the region around it remained in Catalan hands. In 1377, the title of Duke of Athens and Neopatras was assumed by Peter IV of Aragon. It was preserved among the subsidiary titles of his successors, and was regularly included in the full title of the Spanish monarchs at least until the takeover of the Spanish crown by the House of Bourbon.