The centurion (Latin centurion; εκατοντάρχος in greek, hekatontarchos) was one of the degrees of the Roman Army chain of command, however, the news known, it is not possible to define the centurions of the "official" in the modern sense of the term. Index
Each centurion commanded the basic unit of the legion, the centurion (group of men who ranged from 80 to 100 and up to 160 in some cases, although in some sources tells the story of centuries of 300 units. ). The centuries of tradition were associated in pairs to form the handles, in which the two centurions were called prior and posterior. It is unclear whether this corresponded also a precedence in command, most likely was related to the deployment of the enemy (first or second row).
The highest rank among the centurions in a legion centurion was held by the first handful of the first cohort, which was said Primus Pilus (the term pilus has nothing to do with the spear or pilum, the Roman javelin), and he tasks comparable to the modern rank of colonel. The Primus Pilus was the only one of the centurions to enter the war cabinet of a legion and we could say that this is the only role similar to the modern concept of the Journal. 
There is evidence of the presence of two or even three centurions in the same centurion, but still have not been accepted hypothesis for this exception and do not know any implications in the organizational chain of command.
The centurion often did not come from the ranks of the lower orders, in fact for many young aristocrats was the first instance of a military career. No wonder, in fact, that the centurions were young recommended and put in charge of centuries without any war experience. The efficiency of the organization Roman military was only achieved by a military school at the highest level can give you the theoretical tools sufficient for debut and effectively serve as a tribune in a legion even without any experience.
Among the various types of centurion in the literature include the trecenario we do not know exactly the role, but it is believed that for the most part related to the praetorian guard, and the decurion equivalent to the centurion, but to command cavalry units ( see also item Praetorian Guard).
With the reform of Augustus the Roman army, there was also the centurion classiarius, captain of a Navy ship with a hundred Roman miles classiarii (after 70), comparable to a normal centurion "land" also on the basis of his military career (cursus honorum). It could command a trireme. Position Main article: For more, see the entry of the Roman infantry tactics.
The Roman centurions were always positioned in the front line, to give proof of his courage and impetus to its soldiers, for the good outcome of the battle, at least since the time of the Punic Wars. The centurions were in fact located to the right of the schiaramento manipulate later coortale. Position certainly very risky. Not surprisingly often after intense clashes, there were many centurions fell at the end of the battle.
Caesar tells a curious episode in the De bello Gallico, a race between two brave centurions: "There were two centurions in the legion, men of great value, now coming to the most senior, Lucius Vorenus and Titus Pullo. Both were constantly competing for who would excelled over the other, and each year competed by fighting for his career. Pullo, when the fighting along the fortifications was proving harder and said, "What are you waiting Vorenus? Promotion What do you think you get for your value? This day will decide our disputes." Having said this came out of the fortified line and charged the enemy in that part of the line that seemed thicker. So even Vorenus did not stay in the shelter of fortifications and fearing the judgment of his soldiers followed him [in the fighting]. A short distance from the enemy Pullo throws his pilum and stabs a Gaul, who had broken away from the main body of the grid and ran forward. The enemies, while protecting shields with his companion, shot dead and fell to the ground, all together throw their javelins against the centurion, impedengogli backwards. The shield of Pullo is pierced and military belt [holding the sword] is configge auction. This shot moves the sheath and Pullo, while with his right hand trying to draw his sword, is prevented, so that the enemies around him. Rushes to her aid, the opponent Vorenus and helps him in hardships. All enemies then promptly throw against Vorenus, Pullo dropping, believing struck by the javelin. Vorenus fighting a melee with the sword, I killed one and the other pushes back. While incanlza them eagerly, slipping falls on a hole. In its turn is Vorenus that is surrounded and touches to Pullo lend aid. Then both unharmed, after killing many enemies, retreat to the fortifications with great glory. So the luck is both in contention and in combat, which, although opponents are rescued each other and were saved. It was not possible to choose which of the two is superior to the other value. '
(Caesar, De bello Gallico V.44.) Late Empire Main article: For more, see the entries Reform of the Roman Diocletian and Constantine's reform of the Roman army.
With the reform of Constantine and his successors the legion became more and more a tactical unit smaller than that of previous centuries and it seems that it was no longer divided into cohorts. Cohorts disappeared with the rank of centurion and Vegetius mentions to centenarius like his counterpart in the armies tardoimperiali. The reform, however, Constantine did not touch all the units, at least some legions limitanee seems to have maintained an organization similar to the classical one and you have references to figures centurions even the legions of Egypt limitanee Byzantine beginning of the seventh century. Uniform and armament Reconstruction of a Roman centurion of the second century by a group of Italian historian of Rome legio XXX Ulpia Victrix.
Although it is incorrect to apply the concept of "uniformity" typical of modern martiality, the centurion was distinguished by some characteristic elements, one in particular: the crest placed on his helmet was arranged transversely (Crista Transversa), ie from left to right, in contrast to normal soldiers (miles or milites) that could wear it in the longitudinal direction, so that the fray of battle his legionaries could identify more easily. There are other elements, which we mistakenly call "uniformologici", deriving from the sculpture, but they are not for the exclusive use of the centurions: greaves, lorica squamata or muscled, and calcei pterugi.
Another element that is highlighted by the sculpture, which is very often the centurion took the sword to the left instead of right like normal legionnaires, this may indicate that the centurions were usually without a shield.  Duration of the firm and pay Main article: For more, see mission honesta items and pay (Roman army).
Many of the centurions, while its normal stop military (honesta mission) would last no more than 20 years since the time of Augustus, remained in service up to 30-35 years and in a particular case, told by an inscription, it is said that a centurion named Lucius Maximius Gaetulicus, felt up to 57 annual installments, a record.
The salary was to be particularly favorable to his subordinates (dall'optio the simple miles), as well as benefit from your accommodation, as well as being exempt from tribute vacatio munerum imposed the legionaries who wanted to be exempted from service particularly heavy. The centurion, at the height of his career, reaching the rank of primus pilus, was finally able to aspire to have a stipendium between twenty and thirty times (in rare cases up to sixty times) higher than that of an ordinary legionary. Degrees of the centurions from the first century BC the second century A.D. Main article: For more, see the entries Augustan Reform of the Roman army and Primus pilus.
In this section we list the different degrees of the centurions. This diagram shows what could be the tactical organization of the various centuries and the various cohorts, referring to the first centuries of the Roman Empire, from the Augustan reform of the Roman army. A very interesting aspect, which is evident from reading this list, which shall remain valid for some terms, such as princeps and hastatus in the Republican period indicated precisely manipulate the three orders of the structure, but also the provision triplex acies the ranks during the battle . It began, by Decimus hastatus posterior (the last in the list), prior to the Primus pilus (the highest in rank among the centurions within the same Roman legion). The level after which he was entitled, after he had discharged and admitted to the equestrian order, was the praefectus castrorum. Cohors / Orders degree (high to low) centurion's degree (high to low) centurion's degree (high to low) centurion's degree (high to low) centurion's degree (high to low) centurion's degree (high to low) the centurion Cohors I first ordines Primus pilus prior Primus Primus princeps prior hastatus prior (there was) Primus Primus princeps posterior hastatus posterior Cohors II, Secundi ordines pilus prior Secundus Secundus Secundus princeps prior hastatus prior pilus posterior Secundus Secundus Secundus princeps posterior hastatus posterior Cohors III, tertii ordines Tertius pilus prior Tertius princeps prior Tertius hastatus prior Tertius pilus posterior Tertius princeps posterior Tertius hastatus posterior Cohors IIII, pilus prior quarters ordines Quartus Quartus Quartus princeps prior hastatus prior pilus posterior Quartus Quartus Quartus princeps posterior hastatus posterior Cohors V-fifths ordines pilus prior Quintus Quintus Quintus princeps prior hastatus prior pilus posterior Quintus Quintus Quintus princeps posterior hastatus posterior Cohors VI, sexti ordines pilus prior Sextus Sextus Sextus princeps prior hastatus prior pilus posterior Sextus Sextus Sextus princeps posterior hastatus posterior Cohors VII, septimi ordines pilus prior Septimus Septimus Septimus princeps prior hastatus prior pilus posterior Septimus Septimus Septimus princeps posterior hastatus posterior Cohors VIII, Octavi ordines Octavus pilus prior Octavus princeps prior Octavus hastatus prior Octavus pilus posterior Octavus princeps posterior Octavus hastatus posterior Cohors VIIII, noni ordines Nonus pilus prior Nonus princeps prior Nonus hastatus prior Nonus pilus posterior Nonus princeps posterior Nonus hastatus posterior Cohors X, tenths ordines pilus prior Decimus Decimus Decimus princeps prior hastatus prior pilus posterior Decimus Decimus Decimus princeps posterior hastatus posterior Symbol centurionate: vitis or bacillum viteum Reconstruction of a centurion of the Praetorian Guard of the century. A.D. with a lorica muscled (Group III Cohors Praetoria)
The undoubted sign of command of the centurion, is the Vitis, said perhaps more properly Bacillum Viteum, a symbol of authority, but also punitive instrument, consisting of a wooden screw, elastic and knotty to inflict more suffering.
A centurion was called by his legions yield alteram ("Give me another") to the fact that, when a soldier was beating, the Vitis broke and was forced to shout: "Give me another."