Roman cavalry in the context of "Diocletian"

The magister equitum, in English master of the horse or master of the cavalry, was a Roman magistrate appointed as lieutenant to a dictator. His nominal function was to serve as commander of the Roman cavalry in time of war, but just as a dictator could be nominated to respond to other crises, so the magister equitum could operate independently of the cavalry; like the dictator, the appointment of a magister equitum served both military and political purposes.

The spatha was a type of straight and long sword, measuring between 0.5 and 1 metre (20 and 40 inches), with a handle length of between 18 and 20 centimetres (7 and 8 inches), in use in the territory of the Roman Empire during the 1st to 6th centuries AD. Later swords, from the 7th to 10th centuries, like the Viking swords, are recognizable derivatives and sometimes subsumed under the term spatha.

The Roman spatha was used in war and in gladiatorial fights. The spatha of literature appears in the Roman Empire in the 1st century AD as a weapon used by presumably Celtic auxiliaries and gradually became a standard heavy infantry weapon by the 3rd century AD, relegating the gladius to use as a light infantry weapon. The spatha apparently replaced the gladius in the front ranks, giving the infantry more reach when thrusting. While the infantry version had a long point, versions carried by the cavalry had a rounded tip that prevented accidental stabbing of the cavalryman's own foot or horse.

In Ancient Rome, a decury (Latin decuria, plural: decuriae) was a group of ten people, ranged under one chief, or commander, called a decurio.

In Roman cavalry a turma was divided into three decuries.

Martin of Tours (Latin: Martinus Turonensis; 316/336 – 8 November 397) was the third bishop of Tours. He is the patron saint of many communities and organizations across Europe, including France's Third Republic. A native of Pannonia (present-day Hungary), he converted to Christianity at a young age. He served in the Roman cavalry in Gaul, but left military service prior to 361, when he became a disciple of Hilary of Poitiers, establishing the monastery at Ligugé. He was consecrated as Bishop of Caesarodunum (Tours) in 371. As bishop, he was active in the suppression of the remnants of Gallo-Roman religion.

The contemporary hagiographer Sulpicius Severus wrote a Life of St. Martin. He is best known for the account of his using his sword to cut his cloak in two, to give half to a beggar clad only in rags in winter. His shrine in Tours became an often-frequented stop for pilgrims on the road to Santiago de Compostela in Spain.

The auxilia (Classical Latin: [au̯kˈsɪli.a], lit. 'auxiliaries') were introduced as non-citizen troops attached to the citizen legions by Augustus after his reorganisation of the Imperial Roman army from 27 BC. By the 2nd century, the Auxilia contained the same number of infantry as the legions and, in addition, provided almost all of the Roman army's cavalry (especially light cavalry and archers) and more specialised troops. The auxilia thus represented three-fifths of Rome's regular land forces at that time. Like their legionary counterparts, auxiliary recruits were mostly volunteers, not conscripts.

The Auxilia were mainly recruited from the peregrini, free provincial subjects who did not hold Roman citizenship and constituted the vast majority of the population in the 1st and 2nd centuries (c. 90% in the early 1st century). In contrast to the legions, which only admitted Roman citizens, members of the Auxilia could be recruited from territories outside of Roman control.

The Roman legionary (in Latin legionarius; pl.: legionarii) was a citizen soldier of the Roman army. These soldiers would conquer and defend the territories of ancient Rome during the Republic and Principate eras, alongside auxiliary and cavalry detachments. At its height, Roman Legionnaires were viewed as the foremost fighting force in the Roman world, with commentators such as Vegetius praising their fighting effectiveness centuries after the classical Roman legionary disappeared.

Roman legionnaires were recruited from Roman citizens under age 45. They were first predominantly made up of recruits from Roman Italy, but more were recruited from the provinces as time went on. As legionnaires moved into newly conquered provinces, they helped Romanize the native population and helped integrate the disparate regions of the Roman Empire into one polity. They enlisted in a legion for 25 years of service, a change from the early practice of enlisting only for a campaign. Legionnaires were expected to fight, but they also built much of the infrastructure of the Roman Empire and served as a policing force in the provinces. They built large public works projects, such as walls, bridges, and roads. The legionary's last five years of service were on lighter duties. Once retired, a Roman legionary received a parcel of land or its equivalent in money and often became a politically prominent member of society.

The Marian reforms were putative changes to the composition and operation of the Roman army during the late Roman Republic usually attributed to Gaius Marius (a general who was consul in 107, 104–100, and 86 BC). The most important of these concerned the altering of the socio-economic background of the soldiery. Other changes were supposed to have included the introduction of the cohort; the institution of a single form of heavy infantry with uniform equipment; the universal adoption of the eagle standard; and the abolition of the citizen cavalry. It was commonly believed that Marius changed the soldiers' socio-economic background by allowing citizens without property to join the Roman army, a process called "proletarianisation". This was thought to have created a semi-professional class of soldiers motivated by land grants; these soldiers in turn became clients of their generals, who then used them to overthrow the republic.

Belief in a comprehensive scheme of reforms under Marius emerged in 1840s German scholarship, which posited that any changes in the Roman army between the times of Polybius and Marius were attributable to a single reform event. This belief was spread relatively uncritically and was accepted as largely proven by the 1850s and through much of the 20th century. There is, however, little ancient evidence for any permanent or significant change to recruitment practice in Marius' time. The occurrence of such a comprehensive reform led by Marius is no longer widely accepted by specialists; 21st-century scholars have called the reforms a "construct of modern scholarship".