Perhaps most peculiar is the prohibition against marriage in the Imperial army. In the early period, Rome had an army of citizens who left their families and took up arms as the need arose. During the expansionism of the Middle Republic, Rome began acquiring vast territories to be defended as provinces, and during the time of Gaius Marius (d. 86 BC), the army had been professionalized. The ban on marriage began under Augustus (ruled 27 BC–14 AD), perhaps to discourage families from following the army and impairing its mobility. The marriage ban applied to all ranks up to the centurionate; men of the governing classes were exempt. By the 2nd century AD, the stability of the Empire kept most units in permanent forts, where attachments with local women often developed. Although legally these unions could not be formalized as marriages, their value in providing emotional support for the soldiers was recognized. After a soldier was discharged, the couple were granted the right of legal marriage as citizens "(conubium)", and any children they already had were considered to have been born to citizens. Septimius Severus rescinded the ban in 197 AD.