His marriage to a Doukaina made him senior to his elder brother Isaac, and it was Doukai financial and political support that largely facilitated the successful coup that brought him to the throne.

[1][4] [2][5] Before becoming emperor, Constantine X had married into the powerful Dalassenoi family, and took as a second wife Eudokia Makrembolitissa, niece of the Patriarch Michael Keroularios.

[7] Severely undercutting the training and financial support for the armed forces, Constantine X fatally weakened Byzantine defences[citation needed] by disbanding the Armenian local militia of 50,000 men at a crucial point of time, coinciding with the westward advance of the Seljuk Turks and their Turcoman allies.

He also suffered invasions by Alp Arslan in Asia Minor in 1064, resulting in the loss of the Armenian capital,[12] and by the Oghuz Turks in the Balkans in 1065,[13] while Belgrade was lost to the Hungarians.

Eudokia's decision was approved of by Patriarch John Xiphilinos, as due to the Seljuk threat, the army needed to be placed under the command of an able and energetic general.

[18] The first military operations of Romanos took place in 1068 and did achieve a measure of success, although the Byzantine province of Syria came under threat by the Saracens of Aleppo who established themselves at Antioch.

[19] Plans for the campaign season of 1069 were initially thrown into chaos by a rebellion by one of Romanos' Norman mercenaries, Robert Crispin, whose Frankish troops ravaged the Armeniac Theme even after Cripsin was captured and exiled to Abydos.

Romanos managed to pacify the province, and marched towards the Euphrates via Melitene, crossing at Romanopolis, in the hope of retaking Akhlat on Lake Van to protect the Armenian frontier.

[26] When Romanos became aware of what had happened, he tried to recover the situation by making a defiant stand, fighting valiantly even after his horse had been killed under him, but he was wounded in the hand, which prevented him from wielding a sword, and was soon taken prisoner.

[31] John Doukas reneged on the agreement and sent men to have Romanos cruelly blinded on June 29, 1072, before sending him into exile to Prote in the Sea of Marmara.

[32] The emperor's chief interests, shaped by Psellos, were in academic pursuits, and he allowed Nikephoritzes to increase both taxation and luxury spending without properly financing the army.

[citation needed] The underpaid army tended to mutiny, and the Byzantines lost Bari, their last possession in Italy, to the Normans of Robert Guiscard in 1071.

[33] The problem was made worse by the desertion of the Byzantines' western mercenaries, who became the object of the next military expedition in the area, led by the Caesar John Doukas.

[citation needed] A new army under Alexios Komnenos, reinforced by Seljuk troops sent by Malik Shah I, finally defeated the mercenaries and captured John Doukas in 1074.

[34] These misfortunes caused widespread dissatisfaction, exacerbated by the devaluation of the currency, which gave the emperor his nickname Parapinakēs, "minus a quarter".

In the face of the threat posed by Nikephoros Bryennios, his election was ratified by the aristocracy and clergy, while Michael VII resigned the throne with hardly a struggle on 31 March 1078 and retired into the Monastery of Stoudios.

With the help of his general Alexios Komnenos, he defeated Nikephoros Bryennios and other rivals at Kalavrye but failed to clear the invading Turks out of Asia Minor.