St. Martin of Tours was a soldier’s son, at a time when all Legionaries’ sons were forced to join up and do their twenty years in the army also. (Because not enough Romans were joining the army of their own free will. You didn’t need to be a veteran to have a political career anymore, etc.)
So yes, he was essentially drafted. Put in chains. By his dad the tribune, who was for sure going to have his son obey the brand new service law. (St. Martin was a pretty stubborn fifteen year old; and he was the only one in the family who was a Christian, previously having tried his best to get baptized and made a monk at the age of twelve – which didn’t fly with his parents or with the bishop.)
However, he seems to have loved his father despite their disagreements. He didn’t think that war was necessarily immoral, or that soldiers were doing the wrong job (which wasn’t the early Church’s position – they went with St. John the Baptist and Jesus on that). He even supported the legitimacy of the rule of Emperor Julian the Apostate (though of course he warned him that apostasy from Christ and supporting paganism was not good).
He just believed that he had been called to become a hermit monk, and that his place wasn’t in the army, no matter how good a soldier he was. (And he was a very good one, by all accounts.)
So he petitioned the Emperor (yup, Emperor Julian the Apostate) to release him from the army to do service elsewhere. It was both an un-Roman and a very Roman thing to do. And the Emperor did end up releasing him to be a monk, because Julian did have his moments.
