Alexios III Angelos in the context of "Latin Empire of Constantinople"

The Latin Empire, also referred to as the Latin Empire of Constantinople or the Constantinopolitan Empire, was a feudal Crusader state founded by the leaders of the Fourth Crusade on lands captured from the Byzantine Empire. The Latin Empire was intended to replace the Byzantine Empire as the Western-recognized Roman Empire in the east, with a Catholic emperor enthroned in place of the Eastern Orthodox Roman emperors. The main objective to form a Latin Empire was planned over the course of the Fourth Crusade, promoted by crusade leaders such as Boniface I of Montferrat, as well as the Republic of Venice.

The Fourth Crusade had originally been called to retake the Muslim-controlled city of Jerusalem, but a sequence of economic and political events culminated in the Crusader army sacking the city of Constantinople, the capital of the Byzantine Empire. Originally, the plan had been to restore the deposed Byzantine Emperor Isaac II Angelos, who had been usurped by Alexios III Angelos, to the throne. The crusaders had been promised financial and military aid by Isaac's son Alexios IV, with which they had planned to continue to Jerusalem. When the crusaders reached Constantinople, the situation quickly turned volatile, and while Isaac and Alexios briefly ruled, the crusaders did not receive the payment they had hoped for. In April 1204, they captured and plundered the city's enormous wealth.

Michael I Komnenos Doukas, Latinized as Comnenus Ducas (Greek: Μιχαήλ Κομνηνός Δούκας, romanized: Mikhaēl Komnēnos Doukas), and in modern sources often recorded as Michael I Angelos, a name he never used, was the founder and first ruler of the Despotate of Epirus from c. 1205 until his assassination in 1214/15.

Born c. 1170, Michael was a descendant of Alexios I Komnenos and a cousin of emperors Isaac II Angelos and Alexios III Angelos. He began his public career in 1190, as a hostage to the Third Crusade, and went on to serve as governor of the province of Mylasa and Melanoudion in the 1190s and again in c. 1200/01. During the latter tenure he rebelled against Alexios III but was defeated and forced to flee to the Seljuk Turks. In the aftermath of the sack of Constantinople by the Fourth Crusade in 1204, he attached himself to Boniface of Montferrat. Soon, however, he abandoned the Crusader leader and went to Epirus, where he established himself as ruler, apparently through marriage with the daughter or widow of a local magnate.

Gregorios Kamonas (fl. c. 1215 – ?) was a Greek-Albanian lord who ruled the Principality of Arbanon after c. 1215. Demetrios Chomatenos (1216–1236) mentioned him as having the title of sebastos, given to him by the emperor Alexios III Angelos after 1205, during his stay in the Despotate of Epirus at the court of his nephew Michael I Komnenos Doukas. He first married the daughter of Gjin Progoni, then married Serbian princess Komnena Nemanjić, the daughter of King Stefan Nemanjić and widow of Dimitri Progoni, thus inheriting the rule of Arbanon. He strengthened ties with Serbia and secured Arbanon through an Orthodox alliance. He had a daughter together with Komnena, who married Golem of Kruja, the next lord of Kruje.

The struggle for Constantinople was a complex series of conflicts following the dissolution of the Byzantine Empire in the aftermath of the Fourth Crusade in 1204, fought between the Latin Empire established by the Crusaders, various Byzantine successor states, and foreign powers such as the Second Bulgarian Empire and Sultanate of Rum, for control of Constantinople and supremacy within the former imperial territories.

At the time of the Fourth Crusade, the Byzantine Empire was already divided by internal revolts. In the aftermath of the Crusader sack of Constantinople, the empire was dissolved into a patchwork of territories held by various pretenders and warlords. The former Byzantine emperors Alexios III and Alexios V both aspired to retake the capital, though were defeated by the Latins. The early years after 1204 saw the rise and fall of numerous Byzantine statelets; the Latins managed to defeat warlords such as Leo Sgouros but were unable to halt the formation of the more well-organized rump states of the Empire of Nicaea, Empire of Trebizond, and Despotate of Epirus. The prospect of a potential swift Latin conquest of the entire former empire's territories effectively ended when the Bulgarian ruler Kaloyan defeated the Latin army at the Battle of Adrianople (1205).

Andronikos Angelos Doukas (Greek: Ἀνδρόνικος Ἄγγελος Δούκας; c. 1133 – before 1185) was a Byzantine aristocrat related to the ruling Komnenos dynasty. During the reign of his cousin, Manuel I Komnenos, he served without success as a military commander against the Seljuk Turks, and as envoy to the Kingdom of Jerusalem. Following Manuel's death, in 1182, he was sent to stop the rebellion of Andronikos I Komnenos but was defeated and eventually defected to him. Shortly after, he led a failed conspiracy of leading aristocrats against Andronikos I. When it was discovered, Andronikos and his sons fled the Empire, ending up in Acre, where he died. He was the father of emperors Isaac II Angelos and Alexios III Angelos.

Euphrosyne Kastamonitissa (Greek: Εύφροσύνη Κασταμονίτισσα) was a Byzantine noblewoman of the Kastamonites family, a wife of Andronikos Doukas Angelos (a cousin of the ruling Komnenos dynasty) and mother of the two future Byzantine emperors from the Angelos family: Isaac II Angelos and Alexios III Angelos.

Theodora Komnene (Greek: Θεοδώρα Κομνηνή; born 15 January 1096) was a Byzantine noblewoman, being the fourth daughter of Emperor Alexios I Komnenos and Irene Doukaina. She married Constantine Angelos, by whom she had seven children. Byzantine emperors Alexios III Angelos and Isaac II Angelos were her grandsons, thereby making her an ancestor of the Angelos dynasty.