Organisation

 

The auxilia were organised into three types of unit [six types from the second century AD

Cohors Peditata

Infantry units apporximately 500 strong i.e 6 centuries of 80 men

 

Cohors Equitata

Mixed infantry and cavalry units 4 centuries of 80 infantrymen and 4 turmae of 30 cavalrymen

 

Ala

Cavalry units of 500 men apporximately 16 turmae of 30 men. These were descibed as quingenary -500 strong.

 

From the beginning of the 2nd century AD at least some units were enlarged to become milliaria - 1000 strong. This doubled the number of cenuturia and turmae in each unit, it did not double the numbers within each century or turma. It should be noted that these strengths appear to be ‘ideal’ and it would seem that there could be great variation from them, with some units being understrength and others over-strength. Quingery units were commanded by tribunes and milliaria by prefects. However from time to time milliaria could be temporarily split into two halves to allow a detachment to be sent elsewhare. on these occasions it seems thart each half was commanded by a tribune.