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John III Doukas Vatatzes (1192-1254) was the Byzantine Emperor from 1222 to 1254. He was a member of the Palaiologos dynasty and the son of Theodore I Laskaris. Vatatzes was a capable military leader and administrator who expanded the Byzantine Empire to its greatest extent since the 11th century. He died in 1254 and was succeeded by his son Theodore II Laskaris.