Constantine Doukas was the second son of
John I Doukas of
Thessaly by his wife, who is only known by her
monastic name Hypomone ("Patience"). He succeeded his father sometime in or before 1289 as ruler of Thessaly until his death in 1303. From on he bore the title of
sebastokrator. At the beginning of his reign, as he was underage, he stood under the regency of
Anna Palaiologina Kantakouzene. His younger brother
Theodore Angelos was his co-ruler until his own death in ca. 1299. Early in his reign, Constantine's mother entered into negotiations with the
Byzantine Empire and, in exchange for recognizing nominal Byzantine
suzerainty, Constantine was invested with the title of
sebastokratōr. Constantine continued his father's war against
Nikephoros I Komnenos Doukas of
Epirus and his
Angevin allies. The campaign of 1295 resulted in Thessalian occupation of the fortresses that Nikephoros had designated as the
dowry of his daughter
Thamar Angelina Komnene when she married
Philip I of Taranto, son of King
Charles II of Naples and
Maria of Hungary. Most of these conquests were lost to the Angevins in 1296, when a truce was signed. Further fighting followed in 1301, and
Angelokastron in
Aetolia-Acarnania had to be returned to Philip of Taranto. Virtually nothing else is known about the reign of Constantine, who died in 1303. ==Family==