Alexios Strategopoulos led Nicaean forces to recapture Constantinople, leading to the reestablishment of the Byzantine Empire and the end of the Latin Empire.

Alexios Komnenos Strategopoulos was a Byzantine aristocrat and general who rose to the rank of megas domestikos and Caesar. Distantly related to the Komnenian dynasty, he appears in the sources already at an advanced age in the early 1250s, leading armies for the Empire of Nicaea against Epirus. After falling out of favour and being imprisoned by Theodore II Laskaris, Strategopoulos sided with the aristocrats around Michael VIII Palaiologos, and supported him in his rise to the throne after Theodore II's death in 1258. He participated in the Pelagonia campaign in 1259, going on to capture Epirus, but his successes were undone in the next year and he was captured by the Epirotes. Released after a few months, he led the unexpected reconquest of Constantinople from the Latin Empire in July 1261, restoring the Byzantine Empire. He was captured again by the Epirotes in the next year and spent several years in captivity in Italy, before being released. He retired from public affairs and died in the early 1270s.

The Empire of Nicaea, also known as the Nicene Empire, was the largest of the three Byzantine Greek rump states founded by the aristocracy of the Byzantine Empire that fled when Constantinople was occupied by Western European and Venetian armed forces during the Fourth Crusade, a military event known as the Sack of Constantinople. Like the other Byzantine rump states that formed due to the 1204 fracturing of the empire, such as the Empire of Trebizond and the Despotate of Epirus, it was a continuation of the eastern half of the Roman Empire that survived well into the Middle Ages. A fourth state, known in historiography as the Latin Empire, was established by an army of Crusaders and the Republic of Venice after the capture of Constantinople and the surrounding environs.

Constantinople was a historical city located on the Bosporus that served as the capital of the Roman, Byzantine, Latin and Ottoman empires between its consecration in 330 and 1930, when it was renamed Istanbul. Initially as New Rome, Constantinople was founded in 324 during the reign of Constantine the Great on the site of the existing settlement of Byzantium and in 330 became the capital of the Roman Empire. Following the collapse of the Western Roman Empire in the late 5th century, Constantinople remained the capital of the Eastern Roman Empire, the Latin Empire (1204–1261) and the Ottoman Empire (1453–1922). Following the Turkish War of Independence, the Turkish capital moved to Ankara. Although the city had been known as Istanbul since 1453, it was officially renamed Istanbul on 28 March 1930. The city is today the largest city in Europe, straddling the Bosporus strait and lying in both Europe and Asia, and the financial center of Turkey.