Imperial Roman Soldier.

Imperial Roman Army Soldier.

During the period dating 30 BCE-AD 284 the Republican system of citizen conscription was replaced by a standing professional army of mainly volunteers serving standard 20-year terms (plus five years as reservists), although many in the service of the Roman Empire would serve as many as 30 to 40 years on active duty, as established by the first Roman emperor, Augustus (sole ruler 30 BC–14 AD). Regular annual conscription of citizens was abandoned and only decreed in emergencies (e.g. during the Illyrian revolt of 6–9 AD).