Diocletian
Roman emperor who stabilized the empire, initiated the Tetrarchy, and abdicated voluntarily.
Diocletian, also known by the nickname Jovius, ruled as Roman emperor from 284 until he stepped down in 305. Born around 242–245 in the Roman province of Dalmatia, his original name was Diocles, and he came from a low-status family. Like many Illyrian soldiers of his time, he climbed the military ranks, serving under emperors Aurelian and Probus, and eventually became a cavalry commander for Emperor Carus. When Carus and his son Numerian died during a Persian campaign, the troops declared Diocles emperor, and he took the name Diocletianus. Carus’s other son, Carinus, also claimed the throne, but Diocletian defeated him at the Battle of the Margus.
Diocletian’s reign ended the Crisis of the Third Century and stabilized the empire. He began the permanent division of the Roman Empire by appointing his fellow officer Maximian as co-emperor, or Augustus, in 286. Maximian ruled the Western Empire, while Diocletian, as the senior Augustus, governed the Eastern Empire. In 293, he further delegated power by naming Galerius and Constantius as junior colleagues, each with the title Caesar, serving under himself and Maximian respectively. This system, called the Tetrarchy, or “rule of four,” gave each tetrarch control over a quarter of the empire. Diocletian secured the borders and crushed any threats to his rule. Between 285 and 299, he defeated the Sarmatians and Carpi in several campaigns, the Alamanni in 288, and put down usurpers in Egypt from 297 to 298. With Diocletian’s help, Galerius campaigned successfully against Persia, the empire’s longtime enemy, and sacked its capital, Ctesiphon, in 299. Diocletian then led negotiations that resulted in a lasting and favorable peace.
Diocletian reorganized the empire by separating and expanding its civil and military services, and he redrew the provincial divisions, creating the largest and most bureaucratic government the empire had ever seen. He set up new administrative centers in Nicomedia, Mediolanum, Sirmium, and Treverorum, which were closer to the frontiers than the traditional capital at Rome. Building on earlier trends toward absolutism, he presented himself as an autocrat, using elaborate court ceremonies and architecture to set himself above the masses. The growth of bureaucracy and the military, along with constant campaigning and construction, raised state spending and forced a major tax reform. From at least 297 onward, imperial taxation was standardized, made fairer, and generally set at higher rates.
Not everything Diocletian tried worked. His Edict on Maximum Prices in 301, meant to stop inflation through price controls, backfired and was soon ignored. Though effective while he ruled, the Tetrarchy fell apart after his abdication because of competing dynastic claims from Maxentius and Constantine, the sons of Maximian and Constantius. The Diocletianic Persecution from 303 to 312, the empire’s last, largest, and bloodiest official crackdown on Christianity, failed to wipe out the religion. After 324, Christianity became the empire’s preferred religion under Constantine. Despite these setbacks, Diocletian’s reforms fundamentally changed the structure of Roman imperial government and helped stabilize the empire economically and militarily, allowing it to stay largely intact for another 150 years, even though it had been near collapse in his youth. Weakened by illness, Diocletian left office on 1 May 305, becoming the first Roman emperor to voluntarily abdicate. He spent his retirement in his palace on the Dalmatian coast, tending his vegetable gardens. That palace later became the core of the modern city of Split in Croatia.
Diocletian was born in Dalmatia, probably at or near the town of Salona (modern Solin, Croatia), where he later retired. His original name was Diocles (full name Gaius Valerius Diocles), possibly taken from Dioclea, the name of his mother and her supposed birthplace. His official birthday was 22 December, and his birth year is estimated between 242 and 245 based on a report that he was 68 at death. His parents were of low status; the historian Eutropius notes that most writers say he was the son of a scribe, though some claim he was a freedman of a senator named Anullinus. The first forty years of his life are mostly unknown. Diocletian was an Illyricianus who served under Aurelian and Probus. Some scholars think Diocles was trained and promoted by these emperors, but others say there is no reliable evidence of his early career. The 12th-century Byzantine chronicler Joannes Zonaras says he was Dux Moesiae, a commander on the lower Danube. The often-unreliable Historia Augusta claims he served in Gaul, but other sources do not support this, and modern historians ignore it. The first certain point in Diocletian’s career is 282, when Emperor Carus made him commander of the Protectores domestici, the elite cavalry force attached to the imperial household. This post earned him a consulship in 283.
Carus died during a successful war with Persia under mysterious circumstances—some believed he was struck by lightning, others that Persian soldiers killed him. His sons Numerian and Carinus became the new Augusti. Carinus quickly traveled to Rome from Gaul and arrived by January 284, becoming the legitimate emperor in the West. Numerian remained in the East. The Roman withdrawal from Persia was orderly and unopposed, as the Sassanid king Bahram II could not field an army against them.
- born
- 242/245, Dalmatia (probably near Salona)
- died
- 311/312, Dalmatia (retired in his palace on the coast)
- field
- Roman emperor, military commander, administrative reformer
- nationality
- Roman (Illyrian origin)
- known_for
- Ending the Crisis of the Third Century; establishing the Tetrarchy; Diocletianic Persecution of Christians; comprehensive tax and administrative reforms
Lore & Background
Diocletian's reign stabilized the empire and ended the Crisis of the Third Century. He initiated the process of permanently splitting the Roman Empire, appointing fellow officer Maximian as Augustus, co-emperor, in 286. Maximian ruled the Western Empire, while Diocletian reigned in the Eastern Empire as the senior Augustus. In 293, Diocletian delegated further, appointing Galerius and Constantius as junior colleagues (each with the title Caesar), under himself and Maximian respectively. Under the Tetrarchy, or 'rule of four', each tetrarch would rule over a quarter-division of the empire. Diocletian secured the empire's borders and purged it of all threats to his power. He defeated the Sarmatians and Carpi during several campaigns between 285 and 299, the Alamanni in 288, and usurpers in Egypt between 297 and 298. Galerius, aided by Diocletian, campaigned successfully against Persia, the empire's traditional enemy, and in 299, he sacked their capital, Ctesiphon. Diocletian led the subsequent negotiations and achieved a lasting and favorable peace. Diocletian separated and enlarged the empire's civil and military services and reorganized the empire's provincial divisions, establishing the largest and most bureaucratic government in the history of the empire. He established new administrative centers in Nicomedia, Mediolanum, Sirmium, and Treverorum, closer to the empire's frontiers than the traditional capital at Rome. Building on third-century trends towards absolutism, he styled himself an autocrat, elevating himself above the empire's masses with imposing forms of court ceremonies and architecture. Bureaucratic and military growth, constant campaigning, and construction projects increased the state's expenditures and necessitated a comprehensive tax reform. From at least 297 on, imperial taxation was standardized, made more equitable, and levied at generally higher rates. Not all of Diocletian's plans were successful: the Edict on Maximum Prices (301), his attempt to curb inflation via price controls, was counterproductive and quickly ignored. Although effective while he ruled, Diocletian's tetrarchic system collapsed after his abdication due to the competing dynastic claims of Maxentius and Constantine, sons of Maximian and Constantius respectively. The Diocletianic Persecution (303–312), the empire's last, largest, and bloodiest official persecution of C
Reader's Guide
Diocletian was born in Dalmatia, probably at or near the town of Salona (modern Solin, Croatia), to which he retired later in life. His original name was Diocles (in full, Gaius Valerius Diocles), possibly derived from Dioclea, the name of both his mother and her supposed place of birth. Diocletian's official birthday was 22 December, and his year of birth has been estimated at between 242 and 245 based on a statement that he was aged 68 at death (his death year is not certain). His parents were of low status; Eutropius records 'that he is said by most writers to have been the son of a scribe, but by some to have been a freedman of a senator called Anullinus.' The first forty years of his life are mostly obscure. Diocletian was an Illyricianus who served under Aurelian and Probus. According to some scholars Diocles was trained and promoted by Aurelian and Probus, according to other scholars there is no reliable evidence of Diocles's early career. The 12th-century Byzantine chronicler Joannes Zonaras states that he was Dux Moesiae, a commander of forces on the lower Danube. The often-unreliable Historia Augusta states that he served in Gaul, but this is not corroborated by other sources and is ignored by modern historians. The first time Diocletian's whereabouts are accurately established was in 282 when the Emperor Carus made him commander of the Protectores domestici, the elite cavalry force directly attached to the Imperial household. This post earned him the honor of a consulship in 283. After Carus's death, his sons Numerian and Carinus became the new Augusti. Numerian died under suspicious circumstances, and on 20 November 284, the army of the east gathered on a hill outside Nicomedia and unanimously saluted Diocles as their new Augustus. He accepted the purple imperial vestments, raised his sword to the light of the sun, and swore an oath disclaiming responsibility for Numerian's death. He asserted that Aper had killed Numerian and concealed it, then drew his sword and killed Aper. Soon after, Diocles changed his name to the more Latinate 'Diocletianus'. After his accession, Diocletian and Lucius Caesonius Bassus were named as consuls. Diocletian was not the only challenger to Carinus' rule; the usurper Julianus took control of northern Italy and Pannonia after Diocletian's accession, but his forces were weak and dispersed when Carinus' armies moved fr
Did You Know?
- Diocletian was the first Roman emperor to voluntarily abdicate the position.
- His palace on the Dalmatian coast became the core of the modern-day city of Split, Croatia.
- He initiated the process of permanently splitting the Roman Empire, but the split became permanent only later.
- The Diocletianic Persecution (303–312) was the empire's last, largest, and bloodiest official persecution of Christianity.
Notable Quotes (Wikiquote)
"Diocletian (/ˌdaɪ.əˈkliːʃən/; Latin: Gaius Aurelius Valerius Diocletianus Augustus; born Diocles; 22 December 244 – 3 December 311), was a Roman emperor from 284 to 305." — Diocletian "The Genesis of Chemistry, 《A Short History of Chemistry》(1894)." — Diocletian "The reforms of Diocletian were a work of genius and made many people temporarily happy, but failed in the end and added greatly to human misery. I see no reason why this inferior modern copy of them should succeed." — Diocletian "Walter E. Williams, Economics for the Citizen (1978)." — Diocletian
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