Constanti'nus Xi. Ducas
) emperor of the East, A. D. 1059-1067, was chosen by the emperor Isaac I. Comnenus, who abdicated in 1059, as his successor, in preference to his own children, because he thought him to be the most worthy of his subjects.
It proved, however, that, although Constantine was undoubtedly one of the best subjects of Isaac, he still was not fit to rule in those troublous times. Previously to his election, Constantine had been very active in putting Michael VI. Stratioticus on the throne (A. D. 1056), but he deserted him in the following year and espoused the party of Isaac Comnenus, who succeeded in seizing the government. Thence their friendship arose. When he ascended the throne, the people expected that he would take vigorous measures against those swarms of barbarians who were attacking the empire from all sides, and they were the more justified in their expectations as Constantine was an able general.
But he loved talking quite as much as action, and instead of preparing for war, he addressed the people in a long elaborate speech on the duties of an emperor under the circumstances of the times. So fond was he of speeches, that he said he preferred the crown of eloquence to the crown of Rome, nor can we feel sure whether he really meant so or not, for both those crowns were rather dusty then. Having reduced his army from motives of economy, he saw, his empire suddenly invaded (in 1064) by a host, or probably the whole nation, of the Uzes, for they are said to have been 600,000 men strong. While they ravaged Thrace and Macedonia, the Hungarians crossed the Danube and seized Belgrade, the key of the empire. Fortunately for the Greeks, the plague broke out in the camps of those barbarians, and so much diminished their numbers that they hastened back to their steppes beyond the Danube. During the same time the Turks-Seljuks made similar attacks upon the Greek domains in Asia, and the Normans obtained possession of the rest of the emperor's dominions in Italy. Bani, the capital of them, was taken shortly before the death of the emperor, which happened in A. D. 1067. Constantine had many good qualities, though they were overshadowed by petty and strange passions. Love of justice induced him to recall immediately on his accession all those who were exiled for political crimes, and to undertake a great number of lawsuits, which, accustomed as he was to follow his sophistical genius, he believed to be just, while they proved to be mere chicaneries. When it became known that his love of war had turned into love of legal intrigues, many officers of his army abandoned the profession of arms, and became advocates for the purpose of rising to honours and making their fortunes. Constantine conferred the title of Augustus upon his three sons, Michael, Andronicus, and Constantine, who were all under age, and whom he destined to succeed him and to reign conjointly under the regency of his widow Eudoxia.
But she was unable to keep the throne alone, and married Romanus Diogenes for the sake of protection and support, and this distinguished general, who was created emperor, must be considered as the real successor of Constantine XI. (Scylitzes, p. 813, &c., ed. Paris ; Psellus in Zonar. vol. ii. p. 272, &c., ed. Paris ; Glycas, p. 324, &c., ed. Paris; Nicephorus Bryenn. p. 19, &c., ed. Paris.)