Auxilia in the context of "Caligae"

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.

The Imperial Roman Army was the military land force of the Roman Empire from 27 BC to 476 AD, and the final incarnation in the long history of the Roman army. This period is sometimes split into the Principate (27 BC – 284 AD) and the Dominate (284–476) periods.

Under Augustus (r. 27 BC – AD 14), the army consisted of legions, eventually auxilia and also numeri. By the end of Augustus' reign, the imperial army numbered some 250,000 men, equally split between 25 legions and 250 units of auxiliaries. The numbers grew to a peak of about 450,000 by 211, in 33 legions and about 400 auxiliary units. By then, auxiliaries outnumbered legionaries substantially. From this peak, numbers probably underwent a steep decline by 270 due to plague and losses during multiple major invasions by the Germanic Tribal Folk. Numbers were restored to their early 2nd-century level of c. 400,000 (but probably not to their 211 peak) under Diocletian (r. 284–305).

Roman cavalry (Latin: equites Romani) refers to the horse-mounted forces of the Roman army throughout the regal, republican, and imperial eras.

In the regal era, the Roman cavalry was a group of 300 soldiers called celeres, tasked with guarding the Kings of Rome. Later their numbers were doubled to 600, then possibly 1,800. All of the cavalrymen were patricians. In the republican era, the general name for the cavalry was equites and these united consisted of the equestrian class and the first class, with a group of 300 cavalrymen in every legion. They were divided into 10 groups of 30 men. Each group elected three leaders known as decuriones. Later the Roman cavalry stopped using Roman citizens as cavalrymen and relied on Auxilia and foreign recruits.

The Thamud (Arabic: ثَمُود, romanized: Ṯamūd) were an ancient tribe or tribal confederation in pre-Islamic Arabia that occupied the northwestern Arabian Peninsula. They are attested in contemporaneous Mesopotamian and Classical inscriptions, as well as Arabic ones from the eighth century BCE, all the way until the fifth century CE, when they served as Roman auxiliaries. They are also later remembered in pre-Islamic Arabic poetry and Islamic-era sources, including the Quran. Prominently, they appear in the Ruwafa inscriptions discovered in a temple constructed circa 165–169 CE in honor of the local deity, ʾlhʾ.

Islamic sources state that the Thamud were an early Arab tribe that had gone extinct in ancient days. Thamud appears twenty-six times in the Quran, where the tribe is presented as an example of an ancient polytheistic people destroyed by God for their rejection of God's prophet Salih. In the Quran, Thamud is associated with a pattern of rebellion and destruction of past groups of people. This is done the most times with Ad, but others as well, like Lot and Noah. When Salih calls Thamud to serve one God, they demand a sign from him. He presents them with a miraculous she-camel. Thamud, unconvinced, injure the camel; for this, God destroys them, except Salih and his followers. This account is embellished with a more detailed background in the Islamic exegetical tradition. Some traditions locate the tribe in northwestern Arabia at Hegra, and in others they are identified as Nabataeans. Islamic genealogy describes the Thamud as among the true Arab tribes, as opposed to the "Arabicized Arabs".

The siege of Jerusalem in 70 CE was the decisive event of the First Jewish Revolt against the Roman Empire (66–73 CE). Roman forces led by Titus besieged the Jewish capital, the revolt's main stronghold. After months of fighting, they breached the defenses, destroyed the Second Temple, and razed the city, killing, enslaving, or displacing much of its population. The city's fall marked the effective end of the revolt and had far-reaching political, religious, and cultural consequences.

In winter 69/70 CE, after a succession war in Rome, Titus led at least 48,000 troops—including four legions and auxiliary forces—back into Judaea. By spring, this army had encircled Jerusalem, the population of which had surged with refugees and Passover pilgrims. Inside the city, rival factions led by John of Gischala, Simon bar Giora and Eleazar ben Simon fought each other, destroying food supplies and weakening defenses. Although the factions eventually united and mounted fierce resistance, Roman forces breached the city walls and pushed the defenders into the temple precincts.

The Bellum Batonianum (Latin for War of the Batos) or Great Illyrian Revolt was a military conflict fought in the Roman province of Illyricum in the 1st century AD, in which an alliance of native peoples of the two regions of Illyricum, Dalmatia and Pannonia, revolted against the Romans. The Roman historian Suetonius described the uprising as the most difficult conflict faced by Rome since the Punic Wars two centuries earlier.

The rebellion began among native peoples who had been recruited as auxiliary troops for the Roman army. They were led by Bato the Daesitiate, a chieftain of the Daesitiatae in the central part of present-day Bosnia and Herzegovina, and were later joined by the Breuci, a tribe in Pannonia led by Bato the Breucian. Many other tribes in Illyria also joined the revolt.

The Cantabrian Wars (29–19 BC) (Bellum Cantabricum), sometimes also referred to as the Cantabrian and Asturian Wars (Bellum Cantabricum et Asturicum), were the final stage of the two-century long Roman conquest of Hispania, in what today are the provinces of Cantabria, Asturias and León in northwestern Spain.

During the reign of Emperor Augustus, Rome waged a bloody conflict against the Cantabri, the Astures and the Gallaeci still resisting Roman occupation, the last independent Celtic nations of Hispania. These warlike peoples fiercely resisted Roman domination; ten years of war and eight legions with their auxiliary troops – more than 50,000 soldiers in total – were needed to subdue the region.

By the size of the Roman army is meant the changes (increases and reductions) in the number of its contingents: legions, auxiliaries, Praetorian cohorts, Urban cohorts, vigiles, and naval forces over the course of twelve centuries – from 753 BC to AD 476 (the Fall of the Western Roman Empire).

A vexillatio (pl.: 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 (pl.: vexilla), which bore the emblem and name of the parent legion.

Although commonly associated with legions, it is likely that vexillationes included auxiliaries. The term is found in the singular, referring to a single detachment, but is usually used in the plural to refer to an army made up of picked detachments. Vexillationes were assembled ad hoc to meet a crisis on Rome's extensive frontiers, to fight in a civil war, or to undertake an offensive against Rome's neighbours. They varied in size and composition, but usually consisted of about 1000 infantry and/or 500 cavalry.

The limitanei (Latin, also called ripenses), meaning respectively "the soldiers in frontier districts" (from the Latin word limes meaning frontier) or "the soldiers on the riverbank" (from the Rhine and Danube), were an important part of the late Roman and early Byzantine army after the reorganizations of the late 3rd and early 4th centuries. The limitanei, unlike the comitatenses, palatīni, and scholae, garrisoned fortifications along the borders of the Roman Empire and were not normally expected to fight far from their fortifications.

The limitanei were lower-status and lower-paid than the comitatenses and palatīnī, and the distinction in role and status between scholae, palatini, comitatenses, and limitanei had largely replaced the older one between praetorians, legionaries, and auxiliaries. The limitanei and palatini both included legionary units alongside auxiliary units.