| Command Structure of the 1st and 2nd Centuries |
SENIOR COMMAND STRUCTURE
Legatus Legionis
The legati Augusti legionis (legionary commanders) were senators, ex-praetors around thirty years
of age who typically served a 3 (sometimes up to 7) year tour of duty. Legati Augusti pro-praetore
governed Imperial provinces. Those provinces with one legion were commanded by ex-praetors (who
also acted as legionary COs) and those with more by ex-consuls. The latter commanded all of the
provincial legates and their troops (i.e., Britain had four legions).
Tribunus Laticlavius
The second-in-command, a tribune and a senatorial designate around the age of 25, served for one
year. Although command ‘technically’ defaulted to the Tribunus Laticlavius in the absence of the
Legatus, it is more probable that the Praefectus and Tribuni Angusticlavi (see below) assumed
control.
Tribuni Angusticlavi
Each legion had five Tribuni Angusticlavi, equestrian tribunes, who served 3-4 years and then
assumed command of a cavalry ala. They were generally young men (former magistrates and/or
auxiliary cohors peditata/equitata commanders). During the Republic each tribune commanded two
cohorts but in the Principate they occupied staff positions with an administrative/judicial focus.
Tacitus reported that they monitored the performance/reliability of the centurions. Their staff (officium)
was comprised of clerks (cornicularii and secutores) without military responsibilities who recorded
casualties, maintained current lists of men serving, processed furlough applications and dispensed
discharges to retiring veterans. Tribunes often commanded vexillations, detachments of one or more
cohorts on special assignments.
Tribuni Semestres were part of H.Q. staff and served 6 months before resuming civilian life.
Following the Flavian era they were placed in direct command of the legion’s 120 man cavalry
contingent (four turmae of 30 horsemen). The cavalrymen were ranked as non-combatants along
with the headquarters staff. They were attached to specific centuries (as opposed to forming
individual units) and served as messengers and scouts.
Praefectus Castrorum
The third-in-command was an equestrian, a former head centurion in his late 50s with 30 plus years
of experience. He was basically a quartermaster responsible for choosing camp sites and
overseeing their construction inclusive of entrenchments. He inspected tent lines in temporary
camps. During war he supervised the legion’s baggage train, and if siege operations were
anticipated he managed the battering rams and ammunition supplies. In permanent installations he
oversaw the construction of barracks-blocks, internal buildings, wells and aqueducts.
He was the officer in command of the doctors (medici), the surveyors (mensores) and the
horologiarius, the man responsible for the camp clock. He oversaw the supply of construction and
surveying equipment, furnishings, fabrica supplies (inclusive of wood, iron and coal) and medical
equipment for the legion’s hospital (valetudinarium).
Primus Pilus
The fourth-in-command was the senior centurion and leader of the 1st century of the 1st cohort. He
held his post for one year. Parker believes that there were two primi pili, one who commanded troops
in the first cohort and one who served in the Legion’s headquarters.
Princeps
The centurion commanding the second century of the first cohort was next in line, and he was
responsible for the headquarters’ staff as well as training. Ranked below him were the remaining
centurions of the first cohort in the following order - hastatus, princeps posterior and hastatus
posterior.
THE CENTURIONATE AND BELOW
Aquilifer:
He carried the legion’s silver (subsequently gilded) eagle and ranked just below a centurion. He was
entrusted with the legion’s pay chest.
Principales and Immunes:
Below the rank of centurion men were designated as either principales or immunes. Principales
assisted the centurions and were exempt from normal fatigues (optio, signifer and tesserarius).
Immunes, men who were excused from regular fatigues by virtue of special skills (blacksmiths,
carpenters, surveyors, medical assistants, etc.), comprised almost 20% of each unit.
Centurion:
Centurions in cohorts 2-9 were equal in rank with seniority determined by years of service. They were
recognized by their transverse helmet crests, swords worn on the left and their swagger sticks (vitus)
with which they dispensed discipline. They typically rode when a legion was on the march.
Centurions tended to die in service as opposed to retiring to civilian life.
Signifer:
The standard bearers handled the paperwork at century level. Vegetius says that the garrison was
managed by the signiferi who were directly responsible for finances. They recorded financial
transactions, issued receipts, documented account activity and dispensed pay.
Optio:
He was a ‘chosen man’, a centurion-in-training who assumed field command if the unit's centurion
was incapacitated or killed. He carried a staff of office known as a hastile.
Tesserarius:
The tesserarius controlled the daily watchword and was responsible for sentries and other fatigues.
Custos Armorum:
He was responsible for centurial equipment, repairs, and weapons.
Decanus:
A century was composed of 10 mess units of six to ten men who shared a tent and a mule
(contubernia); each was commanded by a decanus.
Miles:
The basic foot soldier served for 20-25 years (depending upon the time period).
Legatus Legionis
The legati Augusti legionis (legionary commanders) were senators, ex-praetors around thirty years
of age who typically served a 3 (sometimes up to 7) year tour of duty. Legati Augusti pro-praetore
governed Imperial provinces. Those provinces with one legion were commanded by ex-praetors (who
also acted as legionary COs) and those with more by ex-consuls. The latter commanded all of the
provincial legates and their troops (i.e., Britain had four legions).
Tribunus Laticlavius
The second-in-command, a tribune and a senatorial designate around the age of 25, served for one
year. Although command ‘technically’ defaulted to the Tribunus Laticlavius in the absence of the
Legatus, it is more probable that the Praefectus and Tribuni Angusticlavi (see below) assumed
control.
Tribuni Angusticlavi
Each legion had five Tribuni Angusticlavi, equestrian tribunes, who served 3-4 years and then
assumed command of a cavalry ala. They were generally young men (former magistrates and/or
auxiliary cohors peditata/equitata commanders). During the Republic each tribune commanded two
cohorts but in the Principate they occupied staff positions with an administrative/judicial focus.
Tacitus reported that they monitored the performance/reliability of the centurions. Their staff (officium)
was comprised of clerks (cornicularii and secutores) without military responsibilities who recorded
casualties, maintained current lists of men serving, processed furlough applications and dispensed
discharges to retiring veterans. Tribunes often commanded vexillations, detachments of one or more
cohorts on special assignments.
Tribuni Semestres were part of H.Q. staff and served 6 months before resuming civilian life.
Following the Flavian era they were placed in direct command of the legion’s 120 man cavalry
contingent (four turmae of 30 horsemen). The cavalrymen were ranked as non-combatants along
with the headquarters staff. They were attached to specific centuries (as opposed to forming
individual units) and served as messengers and scouts.
Praefectus Castrorum
The third-in-command was an equestrian, a former head centurion in his late 50s with 30 plus years
of experience. He was basically a quartermaster responsible for choosing camp sites and
overseeing their construction inclusive of entrenchments. He inspected tent lines in temporary
camps. During war he supervised the legion’s baggage train, and if siege operations were
anticipated he managed the battering rams and ammunition supplies. In permanent installations he
oversaw the construction of barracks-blocks, internal buildings, wells and aqueducts.
He was the officer in command of the doctors (medici), the surveyors (mensores) and the
horologiarius, the man responsible for the camp clock. He oversaw the supply of construction and
surveying equipment, furnishings, fabrica supplies (inclusive of wood, iron and coal) and medical
equipment for the legion’s hospital (valetudinarium).
Primus Pilus
The fourth-in-command was the senior centurion and leader of the 1st century of the 1st cohort. He
held his post for one year. Parker believes that there were two primi pili, one who commanded troops
in the first cohort and one who served in the Legion’s headquarters.
Princeps
The centurion commanding the second century of the first cohort was next in line, and he was
responsible for the headquarters’ staff as well as training. Ranked below him were the remaining
centurions of the first cohort in the following order - hastatus, princeps posterior and hastatus
posterior.
THE CENTURIONATE AND BELOW
Aquilifer:
He carried the legion’s silver (subsequently gilded) eagle and ranked just below a centurion. He was
entrusted with the legion’s pay chest.
Principales and Immunes:
Below the rank of centurion men were designated as either principales or immunes. Principales
assisted the centurions and were exempt from normal fatigues (optio, signifer and tesserarius).
Immunes, men who were excused from regular fatigues by virtue of special skills (blacksmiths,
carpenters, surveyors, medical assistants, etc.), comprised almost 20% of each unit.
Centurion:
Centurions in cohorts 2-9 were equal in rank with seniority determined by years of service. They were
recognized by their transverse helmet crests, swords worn on the left and their swagger sticks (vitus)
with which they dispensed discipline. They typically rode when a legion was on the march.
Centurions tended to die in service as opposed to retiring to civilian life.
Signifer:
The standard bearers handled the paperwork at century level. Vegetius says that the garrison was
managed by the signiferi who were directly responsible for finances. They recorded financial
transactions, issued receipts, documented account activity and dispensed pay.
Optio:
He was a ‘chosen man’, a centurion-in-training who assumed field command if the unit's centurion
was incapacitated or killed. He carried a staff of office known as a hastile.
Tesserarius:
The tesserarius controlled the daily watchword and was responsible for sentries and other fatigues.
Custos Armorum:
He was responsible for centurial equipment, repairs, and weapons.
Decanus:
A century was composed of 10 mess units of six to ten men who shared a tent and a mule
(contubernia); each was commanded by a decanus.
Miles:
The basic foot soldier served for 20-25 years (depending upon the time period).
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