(Ῥωμανὸς ὁ Διογένης), Byzantine emperor from A. D. 1067-1071, was the son of one Constantine Diogenes, a by the rather extravagantt character, who conspired against the emperor Romanus Argyrus, but escaped pursuit by leaping out of a high window. Romallnus Diogenes was the grand-nephew of Romanus Argyrus, through his mother; and enjoying the patronage of the court notwithstanding his either's conduct, soon rose to the dignities of patrician and duke of Sardica or Triaditza. In the reign of Constantine X. Ducas, he solicited the place of Magnus Vestiarius, and having received the answer: "Deserve it through your merite," forth with returned to sardica, sallied out with the garrison, and routed a party of Patzinegue marauders, of whose heads he sent a collection to Constantinople. The emperor returned the compliment by granting him desired appointment, adding: "You owe your preferment not to me, but to your sword." This piqued Romanus; and from that time he entertained schemes of rebellion and of raising himself to the throne. After the death of Conistantine, and duiring the reign of his widow Eudoxia, he became bolder; but his manoeuvres were seen through, and he was arrested, tried, and sentenced to death. Previous to execution he was presented to the empress; and as he had obtained great military renown, and was besides a remarkably handsome man, he made such a visible impression upon Endoxia, that his judges thought it convenient to annul their sentence, in consequence of which he was sent into nominal exile in his native country Cappadocia. Two days after his departure he was ioined by some messengers of the empress, who ordered him to return to Constantinople. At his arrival there he was immediately appointed commander-in-chief of the army. The end of this farce was his marriage with the empress, and his proclamation as emperor three days after their marriage. Constantine X., however, had left three sons, who considered themselves prejudiced through the accession of Romrnanus, and entered into a dantgerouse gerous plot against his life; but their mother scceeded in pacifying them, and submitting them to her authority. There remained, however, a strong party of malcontents at the court, composed of eminent stand hihii-born men. Romans, active and energetic, not only counteracted their plans, but introduced measures of radical reform into the corrupted administration, and freed himself from the authority of his wife, by leaving Constantinople aud keeping his court on the Asiatic side of the Bosporus.

To these domestic quarrels the Turks put a sudconsequence den end. Their sultan, Alp-Arslàn, approached by rapid marches from the shores of the Caspian and the highlands of northern Persia, while one of his lieutenants attacked Syria. Romanus took the field against them with his usual energy and promptitude. His intention was to cover Syria, and he was already on its frontiers when he was informed of the progress of the Turkish arms in the North. He consequently left Syria to his generals, and marched to Pontus with such rapidity, that he surprised and routed several Turkish bodies stationed on its fiontier. This was sufficient to keep the main body of the Turks within Persia. Ro. manus therefore hastened hack to Syria. He made a successful campaign down to Antioch and up again along the Euphrates. and wherever he carried his arms the enemy was worsted. One of his generals, less fortunate, or less skilful, was surprised The Turks, and lost the day and half of his army. Romanus flew to his support; and in a nocturnal engagement, took the camp of the Turks and routed them with great slaughter (20th of November, 1068). He then marched again up the Euphrates as far as Ara, constantly annoyed by the light troops of the enemy; but he placed his troops in good and safe winter-quarters, and returned to the capital. Eudoxia, reconciled to her husband, had meanwhile governed the state with wisdom; and, in acknowledgment of the vicitories of the emperor, presented him with a sort of miscellaneous work, entitled "Ionia," which she had just finished. The campaign was renewed in 1069, and the imperial arms were again successful, though not uniformly so, as the Turks succeeded in taking and pillaging Iconium. The third campaingn in 1070, was carried on under the commandin-chief of Manuel Comnenus, the emperor requir ing repose after so many fatigues. Ere long, news reached the court that Manuel had been defeated and taken prisoner. The emperor was artfully persuaded by some false friends to refrain from taking the command once more, and matters would have taken a bad turn, but for the rare shrewdness of Manuel. It happened that Chrysoscul, the victorious Tcrkish general, pretended to have a better right to the sultanship than Alp-Arslán, and Manuel was no sooner aware of it than, a real Comnene as he was, he persuaded him to desert the sultan, and fly with him to Constantinople, promising him the assistance of the emperor for the recovery of his rights. The vanquished thus led his victor to Constantinople, to the utmost astonishment of the court. Romanus took as much advantage of this strange incident as circumstances would allow; and, in 1071, again set out in person against Alp-Arsldn. But little acquainted with human baseness, line left many of his real friends at home, and took with him many a secret enemy invested with high power. He penetrated as far as the Araxes, not without a manly resistance from the Turks and many a partial defeat of his generals. His position in those wild regions became dangerous, but he stoutly refused the peace offered to him by the sultan. Upon this a pitched battle was fought at Manzicert on the Araxes (26th of August, 1071); and owing to the treachery of some of his officers, no less than to the valour of Alp-Arslán, Romanus lost the day and his liberty. It nas been said that the noble sultan ill-treated his captive, but this is not true, on the contrary he received him well, and discoursed with him as a friend. "What would you have done with me," asked the sultan, "if I had been your prisoner ?" "Beaten you to death," was the By zantine's answer. "I will treat you differently," replied the barbarian infidel, "and according to the precepts of your own religion, which commands humanity and forgiveiess of injuries." Alp-Arslán accordingly gave him 10,000 pieces of gold, and all those prisoners whom the emperor chose to pick out. Upon this a peace was concluded on equitable terms, except a ransom of 1,500,000, and an annual tribute of 360,000 pieces of gold. Ronmanus shed tears when he took leave of his noble victor, who allowed him to return to Constantinople betore the conditions of the treaty of peace were fulfilled. The news of this disaster caused a complete revolution in the capital, so that when Ronmanus appeared at its gates, he was refused admittance. Michael Parapinaces had been raised to the imperial dignity, but Romanus did his utmost to crush him and recover his throne. He was not successful. Twice defeated in pitched battles, he at last surrendered, and was put to death by order of Michael. Romanus left three sons, of whom Nicephorus made himself conspicuous in after years. The reign of Romanus Diogenes, though short, is full of highly interesting events, especially of military adventures, such as those of the noble Scot Ursel or Russell Baliol; but space forbids us to enter upon these details.