Empire of Nicaea

1204 - 1273

The Empire of Nicaea was the largest of the Byzantine Greek rump states established after the occupation of Constantinople in the Fourth Crusade (1204). Founded by the Laskaris family, it existed until 1273, when Emperor Theodoros II Laskaris restored the Roman Empire by recapturing Constantinople. Formation

The Fourth Crusade saw a Western European crusader army besiege and capture Constantinople, capital of the Eastern Roman Empire, and establish the Latin Empire. Though the Latin Empire would claim the entire empire, they were only able to control the area around the Aegean Sea and the Sea of Marmara. Other areas of the Roman Empire coalesced into three states; Nicaea, Epirus, and Trebizond. In the years before the reign of Theodoros II Laskaris, the Empire of Nicaea expanded its territory beyond its initial borders in western Anatolia. Reforms

To strengthen his empire, Theodoros II instituted a number of military reforms, completing many started by his father, Emperor Ioannes III Vatatzes. With the help of trusted advisor Giorgios Mouzalon, he transformed the Nicaean army from a primarily mercenary force to a native Greek army backed by mercenaries. Many soldiers were paid with land, much of which was on the eastern frontier. Greeks were the main beneficiaries of this policy, along with many Cuman immigrants from Europe. To increase the direct loyalty of both military and government officials to the emperor, Theodoros II also tended to appoint officials of low birth, rather than from the aristocracy.

Revolt

The reforms of Theodoros II were not well received by the aristocracy of the empire, who revolted under the leadership of Michael Palaeologus. The rebels are decisively defeated at the Battle of Kyzikos (May 10, 1261). Expansion

Taking advantage of the weakened Seljuk Sultanate of Rum, the Empire of Nicea captured land in central Anatolia (Nicaean-Seljuk War, 1262-1265), almost doubling its territory in Anatolia. In 1266, a combined land-sea force attacked one of the other Roman rump states, the Empire of Trebizond, annexing it in July. In 1269, an alliance of states in the southern Balkans (Epirus, Thessaly, Athens, and Achaia) attacks Nicaea, but are defeated in battle at Pelagonia. Thessaly became a Nicaean vassal, Epirus is annexed. Restoration of Constantinople

In 1272, Nicaea advanced on Constantinople to frighten the Latin Empire, only to discover that much of the garrison and fleet were not in the city, but were attempting to capture the Nicaean island of Daphnusia. Constantinople fell with almost no bloodshed when the Nicaeans were able to sneak into the city. Theodoros II was crowned Emperor of the Romans in the Hagia Sophia in 1273, formally ending the Empire of Nicaea and restoring the Roman Empire.

OTL

Due to Theodoros II’s inherited epilepsy, he died in 1258. His son, Ioannes IV Laskaris, was crowned at the age of seven and reigned as co-emperor with Michael VIII Palaeologus after the assassination of Giorgios Mouzalon. Michael VIII recaptured Constantinople in 1261, restoring the Roman Empire, but did not win a war against the Sultanate of Rum. Ioannes IV was blinded and deposed on December 25, 1261, his eleventh birthday.

https://en.wikipedia.org/wiki/Empire_of_Nicaea