Orrax Penal Legions (pre 577)
For those of you who are interested (or confused), the command structures of my Penitent regiments are loosely based upon those of the Roman Legions. I've not based any of it on the 13th Legion novels of Gav Thorpe.
Regimental Divisions and Associated Ranks
Below is a vague breakdown of the equivalent organisation structure andranks as they might be in a standard Imperial Guard Regiment:
Squad equals Penitentia; Sgt equals Decurion; Corporal equals Optio
Platoon equals Century; Lieutenant equals Centurion (of Second thru Sixth Centuries)
Company equals Cohort; Captain equals Centurion (of First Century)
Regiment equals Legion; Colonel equals Legate (although in the current Founding there is no Legate, Commissar-General Draven is the CO for all three Legions).
Division Compliments
Here follows a quick summary of how many men and sub-divisions there are within a division:
A Penitentia consists of 8 men including the Decurion.
A Century consists of10 Penitentia in addition to the Centurion and his command squad (85 men).
A Cohort consists of 6 Centuries unless it is the 1st Cohort (see below) (510 men).
A Legion consists of 10 Cohorts in addition to the Legate and his command staff (5105 men).
Centurions
There are seven different types of Centurion. The first and foremost of these is the Primus Pilus who commands the 1st Century of the 1st Cohort. He is effectively the Legate's second in command, equivalent perhaps to a major. As such he is superior to all other Centurions in the Regiment. The Centurion of the 1st Century in Cohorts 2-9 is called the Pilus Prior. The Pilus Prior of the 1st Cohort is superior to his counterpart in the 3rd Cohort and so on and so forth. In this way, it is always possible to work out who is in command of the regiment. The other Centurions are called Pilus Posterior (2nd Century), Princeps Prior (3rd Century), Princeps Posterior (4th Century), Hastatus Prior (5th Century), Hastatus Posterior (6th Century).
The 1st Century of the 1st Cohort is a double-strength unit, meaning the 1st Cohort only has 5 Centuries in total. There is, therefore, no Pilus Prior or Hastatus Posterior in the 1st Cohort.
Orrax Regiments are put together utilising volunteers from the Adeptus Arbites. This is why officers of all types are regularly referred to as Wardens (to the men of the regiment they are nothing more than their former prison wardens).
Note that the above criteria are written with Foundings that took place before 557 in mind. The Foundings of 577 and thereafter were much larger and the organisation was altered slightly to accommodate the increased numbers.
Hope this muddies the water some. It even confuses me sometimes.