Constantine III (Western Roman emperor) in the context of "Honorius"

Sub-Roman Britain, also called post-Roman Britain or Dark Age Britain, is the period of late antiquity in Great Britain between the end of Roman rule and the founding of Anglo-Saxon kingdoms. The term was originally used to describe archaeological remains found in 5th- and 6th-century AD sites that hinted at the decay of locally made wares from a previous higher standard under the Roman Empire. It is now used to describe the period that began with the recall of Roman troops from Britannia to Gaul by Constantine III in 407 and ended with the Battle of Deorham in 577. This period has attracted a great deal of academic and popular debate, in part because of the lack of written records from the time.

Constantius III (died 2 September 421) was briefly Western Roman emperor in 421, having earned the throne through his capability as a general under Honorius. By 411 he had achieved the rank of magister militum, and in the same year he suppressed the revolt of the usurper Constantine III. Constantius went on to lead campaigns against various barbarian groups in Hispania and Gaul, recovering much of both for the Western Roman Empire. He married Honorius' sister Galla Placidia in 417, a sign of his ascendant status, and was proclaimed co-emperor by Honorius on 8 February 421. Constantius reigned for seven months before dying on 2 September 421.

The siliqua (pl. siliquas or siliquae) is the modern name—given without any ancient evidence to confirm the designation—to small, thin, Roman silver coins produced in the 4th century and later. When the coins were in circulation, the Latin word siliqua was a unit of weight or value defined by one late Roman writer as one twenty-fourth of a Roman solidus.

The term siliqua comes from the siliqua graeca, the seed of the carob tree, which in the Roman weight system is equivalent to 1⁄6 of a scruple (1⁄1728 of a Roman pound or about 0.19 grams).

Jovinus was a Gallo-Roman senator and claimed to be Roman Emperor (411–413 AD).

Following the defeat of the usurper known as Constantine III, Jovinus was proclaimed emperor at Mainz in 411, a puppet supported by Gundahar, king of the Burgundians, and Goar, king of the Alans. Jovinus kept his position in Gaul for two years, long enough to issue coinage that showed him wearing the imperial diadem. He was supported by a number of local Gallo-Roman nobles who had survived Constantine's defeat.

Gerontius (fl. 407–411) was a general of the Western Roman Empire (with the rank of magister militum), who initially supported the usurper Constantine III, later betraying him in favour of another usurper, Maximus of Hispania.

Constans II (died 411) was the son of the Western Roman emperor Constantine III and served as his co-emperor from 409 to 411. When his father rebelled against the ruling emperor Honorius and the army in Britain acclaimed him as emperor in early 407, Constans was a monk. He was summoned to Gaul, appointed to the position of caesar (heir) and swiftly married so that a dynasty could be founded. In Hispania, Honorius's relatives took up arms in 408 and expelled Constantine's administration. An army under Constans and the general Gerontius was sent to deal with this and re-established Constantine's authority.

Honorius acknowledged Constantine as co-emperor in early 409 and Constantine immediately raised Constans to the position of augustus (emperor), theoretically equal in rank to both Honorius and Constantine. Later in 409 Gerontius rebelled, proclaimed his client Maximus emperor and incited barbarian groups which had recently invaded Gaul to rise up. Constans was sent to Hispania to quash the revolt, but suffered a defeat and withdrew to Arelate (modern Arles). In 410, Constans was sent to Hispania with another army. Gerontius had strengthened his forces with barbarians and won a battle against Constans; the latter withdrew north and was defeated again and killed at Vienne early in 411. Gerontius then besieged Constantine in Arelate and killed him.