Theodore Laskaris was born of a noble but not particularly renowned
Byzantine Greek family of
Constantinople. He was the son of Manuel Laskaris and Joanna Karatzaina.
In 1199, Theodore married
Anna Angelina, daughter of the
Byzantine Emperor Alexios III Angelos and
Euphrosyne Doukaina Kamaterina. By this marriage he was brother-in-law of
Eudokia Angelina.
Theodore later distinguished himself during the sieges of
Constantinople by the Latins of the
Fourth Crusade (1203-1204). He remained in Constantinople until the Latins actually penetrated into the city, at which point he fled across
Bosphorus together with his wife. At about the same time his brother
Constantine Laskaris was unsuccessfully proclaimed emperor by some of the defenders of Constantinople. In
Bithynia Theodore established himself in
Nicaea, which became the chief rallying-point for his countrymen.
At first Theodore did not claim the imperial title, perhaps because his father-in-law and his brother were both still living, perhaps because of the imminent Latin invasion, or perhaps because there was no
Patriarch of Constantinople to crown him emperor. He was proclaimed emperor in 1205 and invited Patriarch
John Kamateros to Nicaea. But John died in 1206 before crowning Theodore. Theodore appointed
Michael IV as the new Patriarch and was crowned by him in March 1208.
In the meantime Theodore had been defeated by the Latins at Adramyttion (
Edremit), but soon afterwards the Latins were themselves defeated by
Kaloyan of Bulgaria at the
Battle of Adrianople. This temporarily stalled the Latin advance, but it was renewed by Emperor
Henry of Flanders in 1206. Theodore entered into an alliance with Kaloyan and took the offensive in 1209. The situation was complicated by the invasion of
Kaykhusraw I of
Rum at the instigation of the deposed Alexios III in 1211, but the Nicaeans defeated and killed the invader in the valley of the
Maeander River near
Pisidian Antioch. Although the danger from Rum and Alexios III was thus neutralized, Emperor Henry defeated Theodore in the same year, and established his control over the southern shores of the
Sea of Marmara. In spite of this defeat, Theodore was able to take advantage of the death of David Megaskomnenos, the brother of Emperor
Alexios I of Trebizond in 1212 and to extend his own control over
Paphlagonia.
In 1214 Theodore concluded a peace treaty with the Latin Empire at Nymphaion, and in 1219 he married a niece of Emperor Henry. In spite of predominantly peaceful relations, Theodore attacked the Latin Empire again in 1220, but peace was restored. Theodore died in November 1221 and was succeeded by his son-in-law
John III Doukas Vatatzes.
At the end of his reign he ruled over a territory roughly coterminous with the old
Roman provinces of
Asia and
Bithynia. Though there is no proof of higher qualities of statesmanship in him, by his courage and military skill he enabled the Byzantine nation not merely to survive, but ultimately to beat back the Latin invasion.
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