Legatus Augusti pro praetore

A legatus Augusti pro praetore (literally: "envoy of the emperor - acting praetor") was the official title of the governor of some imperial provinces of the Roman Empire during the Principate era, normally the larger ones or those where legions were based. Provinces were denoted imperial if their governor was selected by the emperor, in contrast to senatorial provinces, whose governors (called proconsuls) were elected by the Roman Senate.

A legatus Augusti was always a senator of consular or praetorian rank (i.e. who had previously held the office of consul or praetor). However, the position of the governor of Egypt (praefectus Aegypti) was unparalleled, for though an eques (Roman knight) he had legions under his command. Some smaller imperial provinces where no legions were based (e.g. Mauretania, Thrace, Rhaetia, Noricum, and Judaea) were administered by equestrian praefecti (prefects) later designated procuratores (procurators) who commanded only auxiliary forces. The legatus Augusti was both the head of the provincial administration, chief judicial officer and commander-in-chief of all military forces based in the province (legions and auxiliaries). The only function outside the remit of the legatus was finance (the collection of imperial taxes and revenues), which was handled by an independent procurator, who reported direct to the emperor.

...
Wikipedia