Marian reforms
The Roman legionary (in Latin "legionarius", plural "legionarii") was a professional heavy infantryman of the Roman army after the Marian reforms. These soldiers would conquer and defend the territories of ancient Rome during the late Republic and Principate eras, alongside auxiliary and cavalry detachments. At its height, Roman legionaries were viewed as the foremost fighting force in the Roman world, with commentators such as Vegetius praising their fighting effectiveness centuries after the classical Roman legionary disappeared.