A generic title for Roman commanders, became a special title of honour. After a victory the general was acclaimed imperator by his soldiers (see acclamation). He assumed the title after his name until the end of his magistracy or until his triumph. The first certainly attested imperator is Aemilius Paullus (2) in 189 bc. The title was assumed esp. by proconsuls (see pro consule) and gained new importance through Sulla before he was appointed dictator. The increasing influence of the army in the late republic made imperator the symbol of military authority. Sulla occasionally stated (and Pompey emphasized) that he was acclaimed imperator more than once. Caesar first used the title permanently. Agrippa in 38 bc refused a triumph for victories won under Octavian's superior command and established the rule that the princeps should assume the acclamations and the triumphs of his legates. Henceforth, apparently, Octavian used imperator as praenōmen (imperator Caesar, not Caesar imperator). Thus the title came to denote the supreme power and was commonly used in this sense. But, officially, Otho was the first to imitate Augustus, and only with Vespasian did Imperator (‘emperor’) become a title by which the ruler was known. On the death of a princeps, or during a rebellion, the acclamation of a general as an imperator by an army indicated that he was the candidate of that body for the imperial dignity.
The use of the praenomen did not suppress the old usage of imperator after the name. After a victory the emperor registered the salūtātiō imperātōria after his name (e.g.: Imp. Caesar… Traianus…imp. VI).
Subjects: Classical studies