The Empire of Romania (Latin: Imperium Romaniae), more commonly known in historiography as the Latin Empire or Latin Empire of Constantinople, and known to the Byzantines as the Latin Occupation, was a feudal Crusader state founded by the leaders of the Fourth Crusade on lands captured from the Byzantine Empire. It was established after the capture of Constantinople in 1204 and lasted until 1261. The Latin Empire was intended to supplant the Byzantine Empire as the titular Roman Empire in the east, with a Western Roman Catholic emperor enthroned in place of the Eastern Orthodox Roman emperors. Baldwin IX, Count of Flanders, was crowned the first Latin emperor as Baldwin I on 16 May 1204. The Latin Empire failed to attain political or economic dominance over the other Latin powers that had been established in former Byzantine territories in the wake of the Fourth Crusade, especially Venice, and after a short initial period of military successes it went into a steady decline. Weakened by constant warfare with the Bulgarians and the unconquered sections of the empire, it eventually fell when Byzantines recaptured Constantinople under Emperor Michael VIII Palaiologos in 1261. The last Latin emperor, Baldwin II, went into exile, but the imperial title survived, with several pretenders to it, until the 14th century.
The original name of this state in the Latin language was Imperium Romaniae ("Empire of Romania"). This name was used based on the fact that the common name for the Eastern Roman (Byzantine) Empire in this period had been Romania (Ῥωμανία, "Land of the Romans").
The names Byzantine and Latin were not contemporaneous terms. They were invented much later by historians seeking to differentiate between the classical period of the Roman Empire, the medieval period of the Eastern Roman Empire, and the late medieval Latin Empire, all of which called themselves "Roman." The term Latin has been used because the crusaders (Franks, Venetians, and other westerners) were Roman Catholic and used Latin as their liturgical and scholarly language. It is used in contrast to the Eastern Orthodox locals who used Greek in both liturgy and common speech.