Promagistrate

In ancient Rome a promagistrate (Latin: pro magistratu) was an ex consul or ex praetor whose imperium (the power to command an army) was extended at the end of his annual term of office or later. They were called proconsuls and propraetors. This was an innovation created during the Roman Republic. Initially it was intended to provide additional military commanders to support the armies of the consuls (the two annually elected heads of the Republic and its army) or to lead an additional army. With the acquisitions of territories outside Italy which were annexed as provinces, proconsuls and propraetors became provincial governors or administrators. A third type of promagistrate were the proquaestors.

The first type of promagistrate was the proconsul. In the early days of the Roman Republic, when Roman territory was small, Rome had only two legions, each commanded by one of the two consuls. Rome was continually under attack by neighboring peoples (the Etruscans in the north, the Sabines in the east and the Volsci and Aequi in the south). Dionysius of Halicarnassus recorded five instances when a proconsul was appointed between 480 BC and 464 BC. In 480 BC a proconsul led the left wing of an army which combined the two consular legions while the consuls led the centre and the other wing. In 478 BC two proconsuls are mentioned. One served under the consul who went to fight the Etruscans in the north. Another one commanded a third legion. An extra legion was deployed so that two enemies in the south (the Volsci and Aequi) could be confronted individually with two armies. In 464 BC a proconsul led an irregular force of volunteers and reservists to support a consul whose army was insufficient to match the combined forces of two enemies. Dionysius did not specify the role of the proconsuls on the other occasion. Dionysius described these men as 'legates and proconsuls,' which implied proconsular imperium was directly delegated by the incumbent consul and that the proconsul acted as a sort of deputy of the consul in the military action. It was a temporary measure adopted to deal with an immediate military emergency. In the last of the mentioned occasions, the proconsul was appointed by a decree of the senate and Livy noted that this "form of a decree has ever been deemed to be one of extreme exigency." It seems that in these instances an extra commander was drawn from men who had been previously been consuls because they had prior experience of commanding an army.

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