The Nicaean Empire, also known as the Empire of Nicaea, was a Byzantine successor state that emerged after the Fourth Crusade in 1204. It was established in the city of Nicaea (modern-day İznik, Turkey) and served as a refuge for the Byzantine imperial family and loyalists. The empire played a crucial role in preserving Byzantine culture and governance during a time of fragmentation. The Nicaean Empire sought to reclaim Constantinople, the capital of the Byzantine Empire, which had fallen to the Latin Empire. Under the leadership of emperors like Theodore I Laskaris and John III Doukas Vatatzes, the empire expanded its territory and influence, ultimately contributing to the restoration of the Byzantine Empire in 1261.