Roman Legionnaires were the professional soldiers of the ancient Roman Empire. They were typically Roman citizens who served in the military for a minimum of 25 years. Legionnaires were well-trained in various combat techniques and were equipped with armor, shields, and weapons like the gladius, a short sword used for close combat. Each legionnaire was part of a larger unit called a legion, which could consist of around 5,000 soldiers. The organization and discipline of the Roman legions contributed significantly to the military success of the Roman Empire, allowing it to expand and maintain control over vast territories.