Constantine X Doukas or Ducas (Greek: Κωνσταντίνος Ι΄ Δούκας, Kōnstantinos X Doukas), (1006 – May, 1067) was emperor of the Byzantine Empire from 1059 to 1067.

Reign

Constantine Doukas was the son of Andronikos Doukas, a Paphlagonian nobleman who may have served as governor of the theme of Moesia. Constantine gained influence after he married, as his second wife, Eudokia Makrembolitissa, the niece of Patriarch Michael Keroularios. In 1057, Constantine supported the usurpation of Isaac I Komnenos, but gradually sided with the court bureaucracy against the new emperor's reforms. In spite of this tacit opposition, Constantine was chosen as successor by the ailing Isaac in November, 1059, under the influence of Michael Psellos. Isaac abdicated and on November 24, 1059, Constantine X Doukas was crowned emperor.

The new emperor quickly associated two of his young sons in power, appointed his brother John Doukas as kaisar (Caesar) and embarked on a policy favorable to the interests of the court bureacracy and the church. Severely undercutting the training and financial support for the armed forces, Constantine X fatally weakened Byzantine defences at a crucial point of time, coinciding with the westward advance of the Seljuk Turks and their Turcoman allies.

Constantine became naturally unpopular with the supporters of Isaac within the military aristocracy, who attempted to assassinate him in 1061; he was also unpopular with the general population, after he raised taxes to try to pay the army at long last. Constantine lost most of Byzantine Italy to the Normans under Robert Guiscard, except for the territory around Bari, and also suffered invasions from Alp Arslan in Asia Minor in 1064 and the Uzes in the Balkans in 1065. Already old and unhealthy when he came to power, he died on May 22, 1067 and was succeeded by his young sons under the regency of their mother Eudokia Makrembolitissa.

Family

By his first wife, a daughter of Constantine Dalassenos, Constantine X Doukas had no known children. By his second wife, Eudokia Makrembolitissa, Constantine X had the following issue:

• Michael VII Doukas, who succeeded as emperor.
  
• Andronikos Doukas, co-emperor from 1068 to 1078.
  
• Konstantios Doukas, co-emperor from c. 1060 to 1078, died 1081.
  
• Anna Doukaina, a nun
  
• Theodora Doukaina, who married Domenico Selvo, Doge of Venice.
  
• Zoe Doukaina, who married Adrianos Komnenos, a brother of Emperor Alexios I Komnenos.
  
  

References

• (primary source) Michael Psellus, Chronographia.
  
• The Oxford Dictionary of Byzantium, Oxford University Press, 1991.