We often read that, after the Battle of Actium, the future emperor Augustus (who was at that stage known as ‘Caesar') reduced the pool of 50 or so legions then under arms to a manageable army of 28. Of course, the circumstances of the battle had assisted Augustus in his task, for, although Plutarch claimed that Antony “had fled and left nineteen legions of undefeated soldiers” (Life of Antony 68.2). Orosius reports that he had suffered terrible losses: “of the defeated, 12,000 men are said to have been killed and 6000 injured, of whom 1000 expired during medical treatment” (Histories 6.19.12).
Nor was it a matter of adopting entire units from Antony's army, for it seems that “the mass of Antony's soldiers was incorporated into Caesar's legions, and he sent back to Italy the citizens from both sides who were beyond military age … and dispersed the rest” (Cassius Dio, Roman History 51.3.1). Those men who were discharged received a cash bonus, while Augustus' own veterans also received parcels of land.
Nevertheless, for reasons best known to himself, Augustus (as we shall call him, for convenience) chose to rescue six of Antony's legions from oblivion. He had promised “life and pardon” to the defeated (Velleius Paterculus, 2.85.5). He recognized that it would have been wasteful to disband veteran legions, when their years of experience could prove useful for his own ends – the six legions
