Saint John III Doukas Vatatzes

John III Doukas Vatatzes, Latinized as Ducas Vatatzes (Greek: Ἰωάννης Γ´ Δούκας Βατάτζης, romanized: Iōánnēs Doúkās Vatatzēs; c. 1192 – 3 November 1254), was Emperor of Nicaea from 1221 to 1254. He was succeeded by his son, known as Theodore II Doukas Laskaris. John Doukas Vatatzes, born c. 1192 in Didymoteicho, was probably the son of the general Basil Vatatzes, who was killed in battle in 1194, and his wife, a cousin of the Emperors Isaac II Angelos and Alexios III Angelos. John Doukas Vatatzes had two older brothers. The eldest was Isaac Doukas Vatatzes (1188–1261), while his younger brother died at a young age. Through his marriage to Eudokia Angelina he fathered Theodora Doukaina Vatatzaina, who later married Michael VIII Palaiologos. The middle brother's name is unknown, but his daughter married the protovestiarios Alexios Raoul. A successful soldier from a military family, John had risen to the position of protovestiarites when he was chosen c. 1216 by Emperor Theodore I Komnenos Laskaris as the second husband for his daughter Irene Laskarina, following the death of her first husband, Andronikos Palaiologos. As husband of Laskaris' firstborn, who had no son of his own, John may have been the de facto heir to the throne, though the question of succession was left open; Laskaris may have hoped his own marriage to Maria of Courtenay in 1219 would produce a male heir. As a result, when John III became emperor in December 1221, following Theodore I's death in November, he had to suppress opposition to his rule by Laskaris' brothers, Alexios and Isaac. The struggle ended with the Battle of Poimanenon in 1224, in which his opponents were defeated in spite of support from the Latin Empire of Constantinople. John III's victory led to territorial concessions by the Latin Empire in 1225, followed by John's incursion into Europe, where he seized Adrianople.