The Crown of Aragon (UK: /ˈærəɡən/, US: /-ɡɒn/) was a composite monarchy ruled by one king, originated by the dynastic union of the Kingdom of Aragon and the County of Barcelona (later Principality of Catalonia) and ended as a consequence of the War of the Spanish Succession. At the height of its power in the 14th and 15th centuries, the Crown of Aragon was a thalassocracy controlling a large portion of present-day eastern Iberian Peninsula, parts of what is now southern France.