Cohort commander?

[Nathan Ross]

No, you're quite right. Must've had a good patron. Let's hope he was a quick learner.

Ah, that's a relief. I was getting ready to eat my hat

Actually I wonder if Modestus (and he probably wasn't the only teenage centurion in Roman history) and the smattering of younger cohort prefects might have been sons of primipilares or senior centurions. Saturius Picens (prefect at 19) was the son of a primus pilus, and Claudius Claudianus (died aged 24 while 'applying for military service') was the son of a praetorian centurion. Perhaps having a vir militaris family helped boost a young man into the officer's club?

Sometimes I wonder, how the romans ever could conquer anything beyond Romes city wall.

We might think so, but armies in the past often had very young officers. There were plenty of 18-year-old lieutenants in (for example) the British army in the first world war, who died leading their men. When you consider that these youths had probably known little more than school rifle club and a year or so of university, you can see that a Roman aristocrat of the same age (surrounded by slaves from birth, accustomed to effortless exercise of authority, trained in militaristic sports and drills and possibly (in the case of primipilares sons) even growing up in a military environment) would have been far better suited to command.