Aulus Hirtius (ca. 90–43 BC) was one of the consuls of the Roman Republic and a writer on military subjects. He was a legate of Julius Caesar's starting around 54 BC and served as an envoy to Pompey in 50. It was reported that Hirtius dined with Caesar, Sallust, Oppius, Balbus and Sulpicus Rufus on the night after Caesar's famous crossing over the Rubicon river into Italy January 10. During the Roman Civil Wars he served in Spain, he might have been a tribune in 48, and in 47 was at Antioch. He was a praetor in 46 and governor of Transalpine Gaul in 45.