▁the ▁construction ▁of ▁the ▁Pra et or ian ▁camp ▁in ▁ 2 3 ▁BC , ▁there ▁was ▁another ▁similar ▁serving ▁trib une ▁placed ▁in ▁the ▁Pra et or ian ▁camp ▁accordingly . ▁Their ▁functions ▁included , ▁among ▁many , ▁the ▁esc ort ▁of ▁the ▁em peror ▁and ▁the ▁members ▁of ▁the ▁imperial ▁family , ▁and ▁if ▁necessary ▁to ▁act ▁as ▁a ▁sort ▁of ▁anti - ri ot ▁police . ▁C ertain ▁Em press es ▁exclus ively ▁commanded ▁their ▁own ▁Pra et or ian ▁Guard . ▁ ▁According ▁to ▁T ac it us , ▁in ▁the ▁year ▁ 2 3 ▁BC , ▁there ▁were ▁nine ▁Pra et or ian ▁coh ort s ▁( 4 5 0 0 ▁men , ▁the ▁equivalent ▁of ▁a ▁leg ion ) ▁to ▁maintain ▁peace ▁in ▁Italy ; ▁three ▁were ▁station ed ▁in ▁Rome , ▁and ▁the ▁others , ▁nearby . ▁ ▁Their ▁mand atory ▁service ▁period ▁was ▁shorter ▁than ▁that ▁of ▁the ▁leg ion aries : ▁ 1 2 ▁years ▁with ▁the ▁Pra et ori ans ▁instead ▁of ▁ 1 6 ▁years ▁in ▁the ▁leg ions ▁in ▁ 1 3 ▁BC : ▁these ▁were ▁increased ▁respectively ▁to ▁ 1 6 ▁and ▁ 2 0 ▁years ▁in ▁year ▁ 5 ▁BC ▁according ▁to ▁T ac it us , ▁and ▁their ▁pay ▁was ▁higher ▁than ▁that ▁of ▁a ▁leg ion ary . ▁ ▁An ▁ins cription ▁recently ▁discovered ▁suggests ▁that , ▁towards ▁the ▁end ▁of ▁the ▁reign ▁of ▁August us , ▁the ▁number ▁of ▁coh ort s ▁increased ▁to ▁ 1