EMPEROR, a title formerly borne by the sovereigns of the Roman empire (see EMPIRE), and since their time, partly by derivation, partly by imitation, used by a variety of other sov ereigns. Under the republic, the term imperator applied in theory to any magistrate vested with imperium; but in practice it was only used of a magistrate who was acting abroad (militiae) and was thus in command of troops. The term imperator was the natural and regular designation employed by his troops in address ing such a magistrate ; but it was specially employed by them to salute him after a victory; and when he had been thus saluted he could use the title of imperator in public till the day of his triumph at Rome, after which it would lapse along with his imperium. The senate itself might, in the later republic, invite a victorious general to assume the title ; and in these two customs—the salutation of the troops and the invitation of the senate—we see in the germ the two methods by which under the empire the princeps was designated; while in the military connotation attaching to the name even under the republic we can detect in advance the military character by which the emperor and the empire were afterwards distinguished. Julius Caesar was the first who used the title continuously (from 58 B.C. to his death in 44 B.c.), as well domi as militiae; and his nephew Augustus took a further step when he made the term imperator a praenomen, a practice which after the time of Nero becomes regular. But apart from this amalgamation of the term with his regular name, and the private right to its use which that bestowed, every emperor had an additional and double right to the title on public grounds, possessed as he was of an imperium infinitum maius, and com manding all the troops of the empire. The title imperator was con ferred by the senate; and an emperor normally dates his reign from the day of his salutation by the senate. But the troops were also regarded as still retaining the right of saluting an imperator; and there were emperors who regarded themselves as created by such salutation and dated their rights accordingly. The military associations of the term thus resulted, only too often, in making the emperor the nominee of a turbulent soldiery.
Augustus had been designated (not indeed officially, but none the less regularly) as princeps—the first citizen of the State. The designation suited the early years of the empire, in which a dyarchy of princeps and senate had been maintained. But by the 2nd century the dyarchy is passing into a monarchy : the title of princeps recedes, and the title of imperator comes into prominence to designate not merely the possessor of a certain imperium, or the general of troops, but the simple monarch in the fullness of his power as head of the State. From the days of Diocletian there are occasionally two emperors, but not, at any rate in theory, two empires; the two emperors are the dual sovereigns of a single realm. But from the time of Arcadius and Honorius (A.D. 395) there are in reality (though not in theory) two em pires as well as two emperors, one of the East and one of the West.
On the revival of the Roman empire in the West by Charle magne in Boo, the title (at first in the form imperator, or impera tor augustus, afterwards Romanorum imperator augustus) was taken by him and by his Frankish, Italian and German successors, heads of the Holy Roman empire, down to the abdication of the Emperor Francis II. in 1806. The doctrine had, however, grown up in the earlier middle ages (about the time of the Emperor Henry II., 1002-24) that although the emperor was chosen in Germany (at first by the nation, afterwards by a small body of electors), and entitled from the moment of his election to be crowned in Rome by the pope, he could not use the title of emperor until that coronation had actually taken place. The Ger man sovereign, therefore, though he exercised, as soon as chosen, full imperial powers both in Germany and Italy, called himself merely "king of the Romans" (Romanorum rex semper augustus) until he had received the sacred crown in the sacred city.
In mediaeval times the emperor, conceived as vicegerent of God and co-regent with the pope in government of the Christian people committed to his charge, might almost be regarded as an ecclesiastical officer. Not only was his function regarded as con sisting in the defence and extension of true religion; he was him self arrayed in ecclesiastical vestments at his coronation; he was ordained a subdeacon; and, assisting the pope in the celebration of the Eucharist, he communicated in both kinds as a clerk. The same sort of ecclesiastical character came also to be attached to the tsarsl of Russia, who—especially in their relations with the Orthodox Eastern Church—might have vindicated for themselves word Tsar, like the German Kaiser, is derived from Caesar (see TSAR) . Peter the Great introduced the use of the style "Imperator," and the official designation afterwards became "Emperor of all the Russias, Tsar of Poland, and Grand Duke of Finland," though the term tsar was still popularly used in Russia.
(though the sultans of Turkey have disputed the claim) the succession to the East Roman emperors (see EMPIRE). But the title of emperor was also used in the middle ages, and is still used, in a loose and vague sense, without any ecclesiastical connotation or hint of connection with Rome (the two attributes which should properly distinguish an emperor), and merely in order to desig nate a non-European ruler with a large extent of territory. It was thus applied to the rulers of China and Japan; it was attrib uted to the Mogul sovereigns of India; and since 1876 it has been used by British monarchs in their capacity of sovereigns of India (Kaiser-i-Hind) .' Since the French Revolution and during the course of the 19th century the term emperor has had an eventful history. In 1 804 Napoleon took the title of "Emperor of the French," and posed as the reviver of the empire of Charlemagne. Afraid that Napo leon would next proceed to deprive him of his title of Holy Roman emperor, Francis II., in 1804, invested himself with a new title, that of "Hereditary Emperor of Austria," and then, in 1806, abdicated his old, historical title and dissolved the Holy Roman empire. Thus the old and true sense of the term emperor —the sense in which it was connected with the Church in the present and with Rome in the past—finally perished; and the term became partly an apanage of Bonapartism (Louis Napoleon resuscitated it as Napoleon III. in 1853), and partly a personal title of the Hapsburgs as rulers of their various family territories. In 1870, however, a new use of the title was begun, when the union of Germany was achieved, and the Prussian king, who be came the head of united Germany, received in that capacity the title of German emperor. Here the title of emperor designated the president of a federal State; and here the Holy Roman em peror of the 17th and 18th centuries, the president of a loose con federation of German States, may be said to have found his suc cessor. But the term has been widely and loosely used in the course of the 19th century. It was the style from 1821 to 1889 of the princes of the house of Braganza who ruled in Brazil; it has been assumed by usurpers in Haiti, and in Mexico it was borne by Augustin Iturbide in 1822 and 1823, and by the ill-fated Arch duke Maximilian of Austria from 1 864 to 1867.
See J. Selden, Titles of Honour (1672) ; Sir E. Colebrooke, "On Imperial and Other Titles" in the Journal of the Royal Asiatic Society (1877) ; J. Bryce, Holy Roman Empire (1904). See also the articles on "Imperator" and "Princeps" in Smith's Dictionary of Greek and Roman Antiquities.