Infantry units and formations of ancient Rome

Roman military unit

Hastati (: hastatus) were a class of infantry employed in the armies of the early Roman Republic, who originally fought as spearmen and later as swordsmen. These soldiers were the staple unit after Rome threw off Etruscan rule. They were originally some of the poorest men in the legion, and could afford only modest equipment—light chainmail and other miscellaneous equipment. The Senate supplied their soldiers with only a short stabbing sword, the gladius, and their distinctive squared shield, the scutum. The hastatus was typically equipped with these, and one or two soft iron tipped throwing s

Centuria (; : centuriae) is a Latin term (from the stem centum meaning one hundred) denoting military units originally consisting of 100 men. The size of the centuria changed over time, and from the first century BC through most of the imperial era the standard size of a centuria was 80 soldiers. By the time of the Roman Empire, ordo became a synonym of centuria (in 4 BC it was used for a maniple). Ten contuberniums formed a century, composed of 80 legionaries. Commanding this unit was the centurion, a veteran expert in combat analogous to a non-commissioned officer. His role was not only that

Defensive shield wall used by Roman Legions

tactical unit of the Roman legion

thumb|Veles Velites (; : ) were a class of infantry in the Roman army of the mid-Republic from 211 to 107 BC. Velites were light infantry and skirmishers armed with javelins (), each with a 75cm (30 inch) wooden shaft the diameter of a finger, with a 25cm (10 inch) narrow metal point, to fling at the enemy. They also carried short thrusting swords, or gladii, for use in melee. They rarely wore armour as they were the youngest and poorest soldiers in the legion and could not afford much equipment, but they did carry small wooden shields called parma for protection. The velites were placed at th

thumb|Replica triarius metal mail armor, gladius and shield on display at the Flavian Amphitheater, Rome, Italy Triarii (: triarius) ("the third liners") were one of the elements of the early Roman military manipular legions of the early Roman Republic (509 BC – 107 BC). They were the oldest and among the wealthiest men in the army and could afford high quality equipment. They wore heavy metal armor and carried large shields, their usual position being the third battle line. They were equipped with spears and were considered to be elite soldiers among the legion.

Principes (: princeps) were spearmen, and later swordsmen, in the armies of the early Roman Republic. They were men in the prime of their lives who were fairly wealthy, and could afford decent equipment. They were the heavier infantry of the legion who carried large shields and wore good quality armor.

thumb|A re-enactor portraying a Roman infantry soldier of the Late Antiquity

A vexillatio (: vexillationes) was a detachment of a Roman legion formed as a temporary task force created by the Roman army of the Principate. It was named from the standard carried by legionary detachments, the vexillum (: vexilla), which bore the emblem and name of the parent legion.

Roman Army squad

body of troops in ancient Roman

thumb|upright|Inscription about a frumentarius from Legio VII Gemina.

The term accensi (: accensus) is applied to two different groups. Originally, the accensi were light infantry in the armies of the early Roman Republic. They were the poorest men in the legion, and could not afford much equipment. They did not wear armour or carry shields, and their usual position was part of the third battle line. They fought in a loose formation, supporting the heavier troops. They were eventually phased out by the time of Second Punic War. In the later Roman Republic the term was used for civil servants who assisted the elected magistrates, particularly in the courts, where

The speculatores, also known as the speculatores augusti or the exploratores, were an ancient Roman reconnaissance agency. They were part of the consularis and were used by the Roman military. The speculatores were headquartered in the Castra Peregrina.

thumb | right | alt=depiction of the use of arrows in combat | Sagittarii combat Sagittarii (Latin, plural form of sagittarius) is the Latin term for archers. The term sagittariorum in the title of an infantry or cavalry unit indicated a specialized archer regiment. Regular auxiliary units of foot and horse archers appeared in the Roman army during the early empire. During the Principate roughly two thirds of all archers were on foot and one third were horse archers. Mercenary foot archers already served with the Roman republican army, but horse archers were only introduced after the Romans ca

Rorarii were soldiers who formed the final lines, or else provided a reserve thereby, in the ancient pre-Marian Roman army. They may have been used with the triarii in battle near the final stages of fighting, since they are recorded as being located at the rear of the main battle formation.

late Roman imperial guard units

Leves (: levis) were javelin-armed skirmishers in the army of the early Roman Republic. They were typically some of the youngest and poorest men in the legion, and could not afford much equipment. They were usually outfitted with just a number of light javelins and no other equipment. There were 300 leves in a legion, and unlike other infantry types they did not form their own units, but were assigned to units of hastati – heavier sword-armed troops. Their primary purpose on the battlefield was to harass the enemy with javelin fire and support the heavy infantry who fought in hand-to-hand comb