Flavius Honorius was born in 384, the son of the emperor Theodosius and Aelia Flacilla. He was proclaimed as co-emperor by his father in 393. When Theodosius died in 395, Honorius and his older brother Arcadius were left in control of the empire. Though the empire had been split before, this was the final time - though there were still relations between east and west, the entire empire was never again ruled by one person.

Honorius was only 11 when he assumed control of the western Roman empire and (like his brother) was ruled over by powerful advisors. Theodosius had placed Honorius in the care of the half-Vandal general Stilicho, who had been the leading general of the west under Theodosius. Honorius married both of Stilicho's daughters in turn - Maria around 398, and Thermantia in 408. Stilicho was a very loyal and gifted general, but was virtually ruling through Honorius. When Stilicho and the western Roman army marched against the Visigoths who were invading Greece, the eastern emperor wrote Stilicho ordering him out of the estern territory. Later western help was welcome against barbaric incursions in the east. In site of his many successes, Stilicho fell victim to anti-German court intrigue and Honorius had him killed in 408.

Honorius faced many revolts, and coins from these rebels can be found, though are generally rare. There were also heavy invasions of the west from Germanic tribes, such as the Visigoths, Ostrogoths, Burgundians, Alans, Suevi, Franks, and Vandals (the last, after the death of Stilicho.) Honorius left all military operations to his generals. Many areas were lost temporarily, though all but one - Britain - was eventually recovered.

The imperial court started out in Mediolanum (modern Milan) but after the Visigothic invasion of Italy in 402 the court moved to the heavily defended city of Ravenna. The Visigoth leader Alaric demanded 4000 pounds of gold to leave in peace, which the senate recommended Honorius accept. When Honorius refused, the Visigoths, led by Alaric, took Rome by storm 24 August 210. The warriors were left to sack the city for 3 days, but were instructed by Alaric not to hurt the churches or the people.

Honorius died from "dropsy" (a buildup of fluid) on 25 August 423 without leaving any children to carry on the dynasty. He was a completely ineffectual and weak emperor, easily being manipulated into accepting co-emperors and granting land to barbarian tribes. His reign was a significant step in the fall of the western Roman empire.