How was a Roman soldier promoted to Centurion?

Promotion from the ranks of common soldiers: usually it took 15–20 years of service. In the 1st and 2nd century AD a huge number of centurions in Italy came from the Pretorian Guard and not the legions. read more

The very best centurions were then promoted to become centurions in the First Cohort, called Primi Ordines, commanding one of the ten centuries and also taking on a staff role. The most senior centurion of the legion was the Primus Pilus who commanded the first century. read more

A centurion (Latin: centuriō; Greek: hekatontarchos) was a professional officer of the Roman army since the Marian reforms of 107 BC. Most centurions commanded a century (centuria) of eighty men, but the senior centurions commanded cohorts or took senior staff roles in their legion. read more