| Rank | Description | Equivalent |
|---|
| Miles gregarius | Literally, a “common soldier” of the legion. | Private |
| Signifer | Standard-bearer for legion cohort and maniple. No real authority. | Corporal |
| Aquilifer | Eagle-bearer of the legion. Most prestigious post for a standard-bearer. | Corporal |
| Tesserarius | Orderly sergeant; sergeant of the guard. | Sergeant |
| Optio | Second in command of a century and of a cavalry squadron. Unit training, administration, and records officer. | Sergeant major |
| Decurio | Decurion. Officer of Roman cavalry. | Second lieutenant |
| Centurio | Centurion. Officer commanding a century, maniple, and cohort. Sixty to a legion, including six primi ordines. Eleven grades, including primi ordines and primus pilus. Seniority usually determined by length of service. | First lieutenant |
| Primi ordines | Most senior “first rank” centurions of a legion, serving in the first cohort. | Captain |
| Primus pilus | Literally the “first spear,” chief centurion, a legion’s most senior centurion, one of the primi ordines. | Major |
| Praefectus fabricus | Originally prefect of engineers, he became the adjutant of an army commander. | Lieutenant colonel |
| Tribunus militaris | Military tribune, one of six officers of Equestrian Order rank who commanded a legion among them for two months each, on rotation, with the other five each commanding two cohorts of the legion. | Colonel |
| Quaestor | A provincial governor’s chief of staff and quartermaster. On military campaigns often given his own command. By imperial times, while he still had responsibility for military recruiting, his role became a civil one, mostly involving financial and legal affairs. Election as a quaestor also brought a Senate seat for life. | Brigadier general |
| Legatus | A commander of one or more legions or military detachment, of senatorial rank, a deputy of a general of consular rank. | Brigadier general |
| Praetor | A senior magistrate at Rome, second only to the consuls. Praetors and former praetors could command a legion and armies in the field. | Major general |
| Consul | A consul was the highest official at Rome. The two consuls for the year shared the presidency of the Senate and gave their names to the year. Consuls or former consuls normally commanded Roman field armies. Seniority was determined by the number of consulships held and when. For example, Pompey had held two consulships and was therefore senior to all other generals. To eclipse him, Caesar had himself voted four consulships once he was in power, to give him a total of five. | Lieutenant general |
| Proconsul | Governor of a Roman province. A former consul. (See the glossary for details.) | Lieutenant general |
