Late Roman army in the context of "Justinian I"

The fall of the Western Roman Empire, also called the fall of the Roman Empire or the fall of Rome, was the loss of central political control in the Western Roman Empire, a process in which the Empire failed to enforce its rule, and its vast territory was divided among several successor polities. The Roman Empire lost the strengths that had allowed it to exercise effective control over its Western provinces; modern historians posit factors including the effectiveness and numbers of the army, the health and numbers of the Roman population, the strength of the economy, the competence of the emperors, the internal struggles for power, the religious changes of the period, and the efficiency of the civil administration. Increasing pressure from invading peoples outside Roman culture also contributed greatly to the collapse. Climatic changes and both endemic and epidemic disease drove many of these immediate factors. The reasons for the collapse are major subjects of the historiography of the ancient world and they inform much modern discourse on state failure.

In 376, a large migration of Goths and other non-Roman people, fleeing from the Huns, entered the Empire. Roman forces were unable to exterminate, expel or subjugate them (as was their normal practice). In 395, after winning two destructive civil wars, Theodosius I died. He left a collapsing field army, and the Empire divided between the warring ministers of his two incapable sons. Goths and other non-Romans became a force that could challenge either part of the Empire. Further barbarian groups crossed the Rhine and other frontiers. The armed forces of the Western Empire became few and ineffective, and despite brief recoveries under able leaders, central rule was never again effectively consolidated.

A sword is an edged, bladed weapon intended for manual cutting or thrusting. Its blade, longer than a knife or dagger, is attached to a hilt and can be straight or curved. A thrusting sword tends to have a straighter blade with a pointed tip. A slashing sword is more likely to be curved and to have a sharpened cutting edge on one or both sides of the blade. Many swords are designed for both thrusting and slashing. The precise definition of a sword varies by historical epoch and geographic region.

Historically, the sword developed in the Bronze Age, evolving from the dagger; the earliest specimens date to about 1600 BC. The later Iron Age sword remained fairly short and without a crossguard. The spatha, as it developed in the Late Roman army, became the predecessor of the European sword of the Middle Ages, at first adopted as the Migration Period sword, and only in the High Middle Ages, developed into the classical arming sword with crossguard. The word sword continues the Old English, sweord.

The Eastern Roman army refers to the army of the eastern section of the Roman Empire, from the empire's definitive split in 395 AD to the army's reorganization by themes after the permanent loss of Syria, Palestine and Egypt to the Arabs in the 7th century during the Byzantine-Arab Wars. The East Roman army was the continuation of the Late Roman army of the 4th century, until it gradually transformed into what is now called the Byzantine army from the 7th century onwards.

The East Roman army was a direct continuation of the eastern portion of the late Roman army, from before the division of the empire. The East Roman army started with the same basic organization as the late Roman army and its West Roman counterpart, but between the 5th and 7th centuries, the cavalry became more important, the field armies took on more tasks, and the border armies were transformed into local militias.

Stilicho (/ˈstɪlɪkoʊ/; c. 359 – 22 August 408) was a military commander in the Roman army who, for a time, became the most powerful man in the Western Roman Empire. He was partly of Vandal origins and married to Serena, the niece of emperor Theodosius I. He became guardian for the underage Honorius. After years of struggle against barbarian and Roman enemies, political and military disasters finally allowed his enemies in the court of Honorius to remove him from power. His fall culminated in his arrest and execution in 408.

The Valentinian dynasty, commonly known as the Valentinianic dynasty, was a ruling house of five generations of dynasts, including five Roman emperors during late antiquity, lasting nearly a hundred years from the mid fourth to the mid fifth century. They succeeded the Constantinian dynasty (r. 306–363) and reigned over the Roman Empire from 364 to 392 and from 425 to 455, with an interregnum (392–425), during which the Theodosian dynasty ruled and eventually succeeded them. The Theodosians, who intermarried into the Valentinian house, ruled concurrently in the east after 379.

The Valentinian dynasty's patriarch was Gratianus Funarius, whose sons Valentinian I and Valens were both made Roman emperors in 364. Valentinian I's two sons, Gratian and Valentinian II both became emperors. Valentinian I's daughter Galla married Theodosius the Great, the emperor of the eastern empire, who with his descendants formed the Theodosian dynasty (r. 379–457). In turn, their daughter, Galla Placidia married a later emperor, Constantius III (r. 421–421). Their son, Valentinian III (r. 425–455), who ruled in the west, was the last emperor of the dynasty, whose death marked the end of dynasties in the western empire. During the interregnum, Theodosius' son Honorius ruled in the west, and concurrently with Constantius III in 421. The dynasty has been labelled as Pannonian, based on the family origin in Pannonia Secunda in the western Balkans.

Magister militum (Latin for "master of soldiers"; pl.: magistri militum) was a top-level military command used in the late Roman Empire, dating from the reign of Constantine the Great. The term referred to the senior military officer (equivalent to a war theatre commander, the emperor remaining the supreme commander) of the empire. The office continued to exist and evolve during the early Byzantine Empire. In Greek sources, the term is translated either as strategos or as stratelates (although these terms were also used non-technically to refer to commanders of different ranks).