Union of the Kingdom of Aragon and the County of Barcelona
Conquest of the Kingdom of Majorca
Conquest of the Kingdom of Valencia
Conquest of the Kingdom of Sardinia
Conquest of the Kingdom of Naples
Napoleon's invasion of Aragon
The Crown of Aragon was a composite monarchy, also nowadays referred to as a confederation of individual polities or kingdoms ruled by one king with a personal and dynastic union of the Kingdom of Aragon and the County of Barcelona. At the height of its power in the 14th and 15th centuries, the Crown of Aragon was a thalassocracy (a state with primarily maritime realms) controlling a large portion of present-day eastern Spain, parts of what is now southern France, and a Mediterranean "empire" which included the Balearic Islands, Sicily, Corsica, Sardinia, Malta, Southern Italy (from 1442) and parts of Greece (until 1388). The component realms of the Crown were not united politically except at the level of the king, who ruled over each autonomous polity according to its own laws, raising funds under each tax structure, dealing separately with each Corts or Cortes. Put in contemporary terms, it has sometimes been considered that the different lands of the Crown of Aragon (mainly the Kingdom of Aragon, the Principality of Catalonia and the Kingdom of Valencia) functioned more as a confederation than as a single kingdom.
However, beginning with George I, the push for unification under a single monarch began. George, an English prince, sought to model his new kingdom after his home. He relied on contradicting peace agreements with both Castile to his west and France to his north to prevent either one from invading him. However, George later became involved in the crises of his brothers in the Wars of the English Succession. George and his son fought a losing war that resulted in war with France and loss of Sicilian possessions. Their descendants pointed to this loss of territory as a need for unification and by the time of John IV, all the territories in the Crown were either united under Aragon (mainland possessions) or in personal union (the islands and Sicily).
The independent Crown of Aragon met its end at the hands of Napoleon in the early 19th century. Aragonese relations fled to Sicily, where they were able to secure independence. Today Aragon is part of the Napoleonic Empire. The title King of Aragon is held by the emperor.