Roman military:

The military of ancient Rome relates to the combined military forces of Rome from the founding of the city of Rome in the 8th century BC to the fall of the Western Roman Empire in the 5th century AD. Originally, the Roman military consisted entirely of the Roman army, but a small navy was first added during the Samnite Wars and later significantly expanded to include specialized ranged Navy and Land Artillery. The Roman military was intertwined with the Roman state much more closely than in a modern Western nation. Josephus describes the Roman people being as if they were "born ready armed." and the Romans were for long periods prepared to engage in almost continuous warfare, absorbing massive losses. For a large part of Rome's history, the Roman state existed as an entity almost solely to support and finance the Roman military. The military's campaign history stretched over 1300 years and saw Roman armies campaigning as far East as Parthia (modern-day Iran), as far south as Africa (modern-day Tunisia) and as far north as the then-legendary Britannia (modern-day England and Northeast Wales). The makeup of the Roman military changed substantially over its history, from its early history as an unsalaried citizen militia to a later professional force. The equipment used by the military altered greatly in type over time, though there were very few technological improvements in weapons manufacture, in common with the rest of the classical world. For much of its history, the vast majority of Rome's forces were maintained at or beyond the limits of its territory, in order to either expand Rome's domain, or protect its existing borders.

Personnel:

At its territorial height, the Roman Empire may have contained between 45 million and 120 million people. Historian Edward Gibbon estimated that the size of the Roman army "most probably formed a standing force of 375,000" men at the Empire's territorial peak in the time of the Roman Emperor Hadrian. This estimate probably included only legionary and auxiliary troops of the Roman army. However, Gibbon states that it is "not... easy to define [the size of the Roman military] with any tolerable accuracy." In the late Imperial period, when vast numbers of foederati were employed by the Romans, Antonio Santosuosso estimated the combined number of men in arms of the two Roman empires numbered closer to 700,000 in total (not all members of a standing army), drawing on data from the Notitia Dignitatum. However, he notes that these figures were probably subject to inflation due to the practice of leaving dead soldiers "on the books" in order to continue to draw their wage and ration. Furthermore, it is irrespective of whether the troops were raised by the Romans or simply hired by them to fight on their behalf.

Evidence has emerged recently that the Roman army may have included women as well as men. Women were never admitted into core units such as the legions, but there is archaeological evidence that some women did serve in the federated troops used in the late Empire. Contemporary sources made no record of this phenomenon and there is no archaeological evidence that suggests that women constituted a significant proportion of troops even amongst the federated troops of the late empire. For the majority of its history, the Roman army was open to male recruits only, and for a greater part of that history only those classified as Roman citizens (as opposed to allies, provincials, freedmen and slaves) were eligible for military service.

Initially, Rome's military consisted of an annual citizen levy performing military service as part of their duty to the state. During this period, the Roman army would prosecute seasonal campaigns against largely local adversaries. As the extent of the territories falling under Roman suzerainty expanded, and the size of the city's forces increased, the soldiery of ancient Rome became increasingly professional and salaried. As a consequence, military service at the lower (non-staff) levels became progressively longer-term. Roman military units of the period were largely homogeneous and highly regulated. The army consisted of units of citizen infantry known as legions (Latin: legiones) as well as non-legionary allied troops known as auxilia. The latter were most commonly called upon to provide light infantry or cavalry support.

Military service in the later empire continued to be salaried and professional for Rome's regular troops. However, the trend of employing allied or mercenary troops was expanded such that these troops came to represent a substantial proportion of Rome's forces. At the same time, the uniformity of structure found in Rome's earlier military forces disappeared. Soldiery of the era ranged from lightly-armed mounted archers to heavy infantry, in regiments of varying size and quality. This was accompanied by a trend in the late empire of an increasing predominance of cavalry rather than infantry troops, as well as a requital of more mobile operations.

Command structure:

The nominal head of the military prior to the establishment of the Roman Republic was the king, although little else is known of the military command structure during this early period. From the Republic onwards, the Senate was the nominal head of the military, but in practice became increasingly subservient to the wishes of their leading citizens, who became known eventually as Emperors: Julius Caesar was named imperator ("commander") and "Father of the Country" and for all intents and purposes "could do as he liked". As the Empire developed, the Emperor became the de facto head of the Roman military. The command structure grew in complexity throughout the Republic and Empire, but a simple representation is presented below:

Military Culture:

Historian Peter Heather describes Roman military culture as being "just like the marines, but much nastier".[7] At least in the legions of the Republic, discipline was fierce and training harsh, all intended to instill a group cohesion or esprit de corps that could bind the men together into effective fighting units. Unlike opponents such as the Gauls, who were fierce individual warriors, Roman military training concentrated on instilling teamwork and maintaining a level head over individual bravery - troops were to maintain exact formations in battle and "despise wild swinging blows"[8] in favour of sheltering behind one's shield and delivering efficient stabs when an opponent made himself vulnerable.

Loyalty was to the Roman state but pride was based in the soldier's unit, to which was attached a military standard - in the case of the legions a legionary eagle. Successful units were awarded with accolades that became part of their official name, such as the 20th legion, which became the XX Valeria Victrix (the "Valiant and Victorious 20th").

Of the martial culture of less elite units such as sailors, and light infantry, less is known, but it is doubtful that its training was as intense or its esprit de corps as strong as in the legions.

Roman Military Equipment:

Although Roman iron-working was enhanced by a process known as carburization, the Romans are not thought to have developed true steel production. From the earliest history of the Roman state to its downfall, Roman arms were therefore uniformly produced from either bronze or, later, iron. As a result the 1300 years of Roman military technology saw little radical change in technological level. Within the bounds of classical military technology, however, Roman arms and armour was developed, discarded, and adopted from other peoples based on changing methods of engagement. It included at various times stabbing daggers and swords, slashing swords, long thrusting spears or pikes, lances, light throwing javelins and darts, slings, and bows.

Roman military personal equipment was produced in large numbers to established patterns and used in an established way. It therefore varied little in design and quality within each historical period. According to Hugh Elton, Roman equipment (especially armor) gave them "a distinct advantage over their barbarian enemies." [29] who were often, as Germanic tribesmen, completely unarmoured. However, Luttwak points out that whilst the uniform possession of armour gave Rome an advantage, the actual standard of each item of Roman equipment was of no better quality than that used by the majority of its adversaries.[30] The relatively low quality of Roman weaponry was primarily a function of its large-scale production, and later factors such as governmental price fixing for certain items, which gave no allowance for quality, and incentivised cheap, poor-quality goods.

The Roman military readily adopted types of arms and armour that were effectively used against them by their enemies. Initially Roman troops were armed after Greek and Etruscan models, using large oval shields and long pikes. On encountering the Celts they adopted much Celtic equipment and again later adopted items such as the gladius from Iberian peoples. Later in Rome's history, it adopted practices such as arming its cavalry with bows in the Parthian style, and even experimented briefly with niche weaponry such as elephants and camel-troops.

Besides personal weaponry, the Roman military adopted team weaponry such as the ballista and developed a naval weapon known as the corvus, a spiked plank used for affixing and boarding enemy ships.