▁from ▁daily ▁ch ores . ▁After ▁another ▁two ▁years ▁he ▁could ▁be ▁promoted ▁to ▁Princi p alis , ▁with ▁a ▁double ▁sal ary , ▁in ▁charge ▁of ▁deliver ing ▁messages ▁( T esser arius ) ▁or ▁as ▁an ▁assistant ▁cent ur ion ▁( Opt io ) ▁or ▁standard ▁bear er ▁( Sign ifer ) ▁at ▁the ▁corps ▁of ▁the ▁century ; ▁or , ▁if ▁liter ate ▁and ▁numer ate , ▁he ▁could ▁join ▁the ▁administrative ▁staff ▁of ▁the ▁pre fect . ▁ ▁Only ▁a ▁few ▁soldiers ▁could ▁att ain ▁the ▁rank ▁of ▁Princi p alis ; ▁however ▁those ▁that ▁did , ▁during ▁the ▁course ▁of ▁their ▁service , ▁were ▁designated ▁Ev oc ati ▁August i ▁by ▁the ▁em peror . ▁This ▁design ation ▁allowed ▁them ▁to ▁be ▁promoted ▁to ▁technical ▁administrative ▁posts , ▁or ▁instruct ors ▁in ▁Rome , ▁or ▁to ▁a ▁century ▁in ▁a ▁leg ion , ▁and ▁accordingly ▁extend ▁their ▁career . ▁C ertain ▁princip alis ▁could ▁at ▁the ▁end ▁of ▁their ▁career ▁be ▁promoted ▁to ▁Cent ur ion ▁in ▁the ▁Guard ; ▁this ▁would ▁be ▁the ▁peak ▁of ▁his ▁career . ▁Anyone ▁am bit ious ▁for ▁further ▁promotion ▁would ▁need ▁to ▁transfer ▁to ▁a ▁leg ion . ▁ ▁The ▁Military ▁trib unes ▁( T rib uni ▁Milit um ) ▁at ▁the ▁head ▁of ▁the ▁coh ort s ▁were ▁Roman ▁caval ry men . ▁In ▁contrast ▁to ▁many ▁superior ▁cad res ▁of ▁the ▁Army , ▁who ▁origin ated ▁from ▁the ▁E quest rian ▁Order , ▁these ▁trib unes ▁started ▁their ▁career