I've read the books of Stephen Dando-Collins extensively. He makes a very compelling case that Roman legionaries were enlisted together, served their term and then were discharged together. In the time between, no legionaries would be enlisted. The legion would of course loose troops due to war, diseases, other causes, and shrink in size. But until the day of the discharge, no replacements would come to that legion. Except under very special circumstances. Most often, auxiliaries would be hired to make up for the lost numbers, until the new recruits came in. Which could be many years in the future.
I'm very much taken by this theory, but do have my doubts. The legions did have specific recruiting areas. And many legions fought as a legion under their own eagle, even when it had only one or a few cohorts.
But recruiting a couple of thousand strong young men would be a serious drain on the available manpower in that region. Tax-wise, that would not be a good idea. Meaning that the harvest of that year and the next couple of years would be a lot less. Those now ex-farm hands would be serving in army, instead of working on the fields.
How did the legions manage their recruitment? Is Dando-Collins correct?
Dando-Collins documents his work excellent. I'm not that good in formulating my question, likely. I'm not talking about centurions, they had a very different career path. Ordinary troops normal didn't have much of a career. They signed on as legionary, and usually retired not higher than imunes status. Making a career (as a common man) wasn't really an option in ancient times.
Assume a legion was raised by Caesar. For example, Legio I Germanica was raised in 48 BC. We can assume that all/most regular legionary were raw recruits, the centurions came (of course) from other legions. Service time was about 12 years, so the surviving legionaries were paid of and retired to become evocati in 36 BC. How many retirees is not so important.
As a new full legion it probably was about 4800 man strong. In those 12 years (later up to 25 years) lots of legionaries would die in combat, become medically unfit or died of natural causes. Probably anywhere between 1000 - 2000 legionaries would retire.
That means about 2800 up to (in my example) 3800 man had to be recruited.
I know each legion had its own area of recruitment, completely unrelated to where the legion was stationed. Recruiting officers recruited new legionaries there, and marched them to where the legion actually was stationed.
Between 48 BC and 36 BC no additional troops were send to make up for the losses, according to Dando. At best the legate or governor could hire extra auxiliaries. That seems entirely plausible to me. But this would, in my opinion, be a very large drain on local manpower, which was necessary to grow food and be productive civilians.
It's not a big deal for an area or province to supply a couple of hundred recruits each year. But supplying 2800-3800 strong young men is a lot. Even if it happens once very 12-25 years. It could affect the local economy seriously.
That's what I try to find out.