Name conventionally applied to the political successor of the Byz. state founded at Constantinople on 13 Apr. 1204 by the Latins of the Fourth Crusade; it lasted until 25 July 1261. Contemporaries called it Romania or Imperium Constantinopolitanum. The Latin Empire claimed sovereignty over all former Byz. territory. While it sought to control its vassal states established in Greece (the kingdom of Thessalonike, the principality of Achaia, the duchy of Athens), it rarely exercised authority outside of Bithynia and eastern Thrace.

After the capture of Constantinople, a committee of 12 electors (six Venetian, six others) chose as emperor Baldwin of Flanders; when he vanished into a Bulgarian prison (1205), his brother Henry of Hainault became regent, then (once Baldwin's death was known) emperor. The most capable of the Latin rulers, Henry secured the allegiance of Thessalonike, Athens, and Achaia and conciliated his Greek subjects. Upon his death (1216), the barons selected Peter of Courtenay, husband of Henry's sister Yolande, but Peter, captured (1217) by Theodore Komnenos Doukas, perished in an Epirote prison. Yolande ruled until her death in 1219. She was eventually succeeded by her son Robert of Courtenay (1221–28). His successor was his brother Baldwin II; because Baldwin was too young to rule, John of Brienne became emperor (1231–37). As emperor, Baldwin II (1240–61) had to spend much of his time in western Europe in quest of assistance. (See table for a list of rulers of the Latin Empire.)

The Latin Empire retained many Byz. institutions. Wearing purple boots, the emperor was crowned in Hagia Sophia according to a modified Byz. ritual. He bestowed Latin versions of Byz. titles, such as cesar, sevastocrator, and protovestiarius, along with Western dignities such as seneschal and constable (B. Hendrickx, Byzantina 9 [1977] 187–217). In reality, the Latin Empire was a feudal state. Three documents formed a “constitution,” which each new emperor was required to uphold: a treaty between the Venetian and non-Venetian Crusaders (Mar. 1204) that provided for election of a Latin emperor and division of the spoils; the Partitio Romaniae (Sept./Oct. 1204); and a treaty (Oct. 1205) that regulated the Venetians' relations to the emperor. A council of Venetian and other barons had an effective veto over the emperor's actions.

To succeed, the Latin Empire needed to reconcile the Greek population to its rule. Constantinople and the smaller towns were for the most part inhabited by Greeks, who initially welcomed the Crusaders. A few Byz. nobles joined the Latins: briefly, Michael I Komnenos Doukas, before leaving to found his state in Epiros; permanently, Theodore Branas, influenced by his relationship with Agnes of France. Emp. Henry won the affection of the Greeks. The fairness of his decisions was celebrated. He appointed Branas ruler of Didymoteichon and Adrianople and tolerated Orthodoxy. His Greek subjects even fought for him against Byz. armies. Later emperors ignored the Greeks; Baldwin II vigorously repudiated the charge of having any Greek members in his council. The emperors relied on their Western vassals—chiefly French, who owed military service for their holdings—and on mercenaries.

Within the Latin Empire, Venice occupied a special position. Although entitled to extensive territories, Venice concentrated its rule on the islands and principal ports. A substantial portion of Constantinople belonged to Venice, which regained all the rights and exemptions it had enjoyed under Byz. Thus, the Venetians paid no commercial taxes, although those who held fiefs were obligated to the usual feudal duties. The Venetians were governed in Constantinople by a podestà and council who, with the leading barons, formed the emperor's council. The Venetians' power to veto imperial actions was reinforced by their near-monopoly of commerce and their control of the only fleet that could provide naval support for the Latin emperors. The podestà was closely controlled by the government of Venice.

Under the preconquest agreement of Mar. 1204, whichever party, Venetian or non-Venetian, did not gain the office of emperor was entitled to choose the patriarch of Constantinople. Thus, in 1204 the Venetians designated their own clerics to form a cathedral chapter for Hagia Sophia; the clerics then elected Thomas Morosini as patriarch. Pope Innocent III presently approved this election and granted papal recognition (previously denied) to Constantinople as a patriarchate. He and his successors sought to loosen Venetian control over the church in the Latin Empire, and until 1261 most later patriarchs were designated by the pope. Although the higher clergy was Latin, the parish priests largely remained Greek. Many refused to recognize the Latin patriarch but turned to the Orthodox patriarch of Constantinople reestablished at Nicaea. The Franciscans and Dominicans won some converts and sponsored some church decoration, notably a cycle of the life of St. Francis at Kalenderhane Camii.

In its early decades, the principal foes of the Latin Empire were to its west. When the Bulgarian Kalojan offered alliance to the victorious Crusaders, the Latins arrogantly rejected him. Kalojan defeated and captured Baldwin I, then killed Boniface of Montferrat in battle. Kalojan's death allowed Emp. Henry to maneuver among the rival Bulgarian claimants Boril, Slav, and Strez; Henry married his illegitimate daughter to Slav and ca.1213 or 1214 himself married a daughter of Boril. The Greek rulers of Epiros were usually rivals, sometimes allies, of the Latin Empire. In 1224 Theodore Komnenos Doukas took Thessalonike, only to fall victim to the revived Bulgaria of John Asen II. The latter appropriated most of the Latin Empire's European territories and boasted in an inscription at Tŭrnovo that the empire survived only by his permission.

Initially, the Crusaders despised the Byz. state re-created at Nicaea; they repeatedly defeated Theodore I Laskaris. But after John Asen's death (1241), John III Vatatzes acquired the territory the Bulgarians had taken from the Latin Empire; his domains enveloped the Latins to the east and west. Only transfusions of funds from western Europe, papal support, and the Venetian fleet preserved Constantinople. Unable to hire sufficient knights, the Latin Empire became so debilitated that even Pope Innocent IV was prepared to accept a Byz. recovery of Constantinople if Vatatzes would acknowledge papal supremacy. When in July 1261 the Venetian fleet departed for an expedition in the Black Sea, the army of Michael VIII Palaiologos was admitted to Constantinople by the citizens. Constantinople again became the Byz. capital, and Baldwin II fled to the West, where the empty title of Latin Emperor lingered through most of the 14th C.Charles M. Brand, Anthony Cutler