The Roman Army was organized into legions of 5,000-6,000 men commanded by a legate. Each legion was divided into ten cohorts made up of six centuries of around 100 men each, commanded by a centurion. Centurions were important leaders responsible for training and discipline. Standard bearers carried symbols of each century into battle. To become a legionary, one had to be a male Roman citizen between 18-20 years old and at least 5'3" tall, expected to serve for 25 years with regular marches while carrying heavy equipment for training. Auxiliary soldiers from conquered lands also served alongside legions.