Empire of Nicaea

successor State of the Byzantine Empire when the crusaders conquered Constantinople at Fourth Crusade of 1204

The Empire of Nicaea (Greek: Βασίλειον τῆς Νίκαιας) was the largest of the Byzantine Greek states founded by the nobility of the Byzantine Empire after Constantinople was conquered during the Fourth Crusade. It lasted from 1204 to 1261.

Empire of Nicaea
Αυτοκρατορία της Νίκαιας
1204–1261
The Latin Empire, Empire of Nicaea, Empire of Trebizond, and the Despotate of Epirus. The borders are very uncertain.
The Latin Empire, Empire of Nicaea, Empire of Trebizond, and the Despotate of Epirus. The borders are very uncertain.
CapitalNicaea
Common languagesGreek
Religion
Eastern Orthodox Church
GovernmentMonarchy
Emperor 
• 1204 – 1222
Theodore I Lascaris
• 1222 – 1254
John III Ducas Vatatzes
• 1254 – 1258
Theodore II Lascaris
• 1258 – 1261
John IV Lascaris
• 1259 – 1261
Michael VIII Palaeologus
Historical eraHigh Medieval
• Established
1204
• Disestablished
July 1261
Preceded by
Succeeded by
Byzantine Empire
Byzantine Empire

It ended in 1261, when Constantinople was recaptured.