Probus defeats the army under Bonosus. Bonosus sees no way out and
hangs himself. His family is treated with
honours.[2]
Julius Saturninus, governor of
Syria, is in
Alexandria, charged with the defense of the East. He is declared emperor and withdraws to
Apamea. Probus besieges the city and puts him to death.[3]
Roman territory is under constant threat of raids from
Franks. The cities in Gaul are reinforced with
defensive walls.[4]
Emperor Wu of the
Jin dynasty completes the unification of China, which was previously divided between three contending powers during the
Three Kingdoms period. The Jin dynasty's capital of
Luoyang becomes a thriving centre of commerce as foreign diplomats and traders travel there.[5]
The praetorian prefect
Marcus Aurelius Carus usurps power in
Raetia. Probus attempts to organise a campaign against Carus but is murdered by his discontented troops in
Sirmium.
Carus defeats the
Quadi and
Sarmatians on the
Danube; for his victories he is given the title Germanicus Maximus.
Exploiting the Persian civil war, Carus leaves Carinus in charge of much of the Roman Empire and, accompanied by his younger son Numerian, invades the
Sassanid Empire. They sack
Seleucia and
Ctesiphon, the capital of the
Persian kingdom, and they press on beyond the
Tigris. For his victories, Carus receives the title of Persicus Maximus.[citation needed]
The officer Diocles, the future Emperor
Diocletian, distinguishes himself in the war against the Persians.[citation needed]
Carinus campaigns with success in Britain and on the Rhine frontier.[citation needed]
Summer: Carus dies in mysterious circumstances during the war against the Persians. Various sources claim he died of illness, was struck by lightning or was killed in combat.[citation needed]
Carinus and
Numerian succeed their father Carus. Numerian, who had accompanied his father into the Persian Empire, leads the army back to Roman territory.[citation needed]
Emperor
Numerian travels through
Bithynia (
Asia Minor) on his way home to
Rome. Suffering from an
inflammation of the eyes, he travels in a closed
litter in which soldiers find his decaying corpse.
November 20 – The commander of Numerian's
domestici (household troops),
Diocles, is chosen to be the new emperor. In a military assembly outside
Nicomedia (modern
İzmit, Turkey), Diocles claims that the praetorian prefect (and rival for the throne) Arrius Aper murdered Numerian, and he personally stabs and kills the prefect on the spot. The new emperor changes his name to the Latinised 'Diocletian'. Building on existing trends, Diocletian presents his rule as that of a god-like
dominus or autocrat.
Sabinus Julianus, the praetorian prefect of Emperor
Carinus, exploits the instability and usurps the throne in northern Italy.
Persian Empire
King of Kings
Bahram II installs
Mirian III, of the House of Mihran, on the throne of the
Kingdom of Iberia. Mirian would rule the kingdom until his death in c. 361.
Korea
Yurye becomes king of the Korean kingdom of
Silla.[9]
Summer –
Battle of the Margus: Emperor
Diocletian defeats the forces of Carinus in the valley of the
Margus (
Serbia). Numerous soldiers desert Carinus during the battle. Carinus then flees to the Pannonian fort of Cornacum, but he is soon slain by his officers.
July 21 or
July 25 – Diocletian appoints his fellow-officer
Maximian to the office of
caesar, or junior co-emperor.
Winter/Spring: The CaesarMaximian defeats the Bagaudae rebellion in Gaul. He then defeats a Germanic invasion into Gaul, defeating an army of
Burgundians and
Alemanni and another army of Chaibones and
Heruli.
Emperor
Diocletian campaigns successfully against
Sarmatian raids. The future emperor
Constantius defeats the 'Bosporian Sarmatians'.
April 1 – Diocletian rewards Maximian by elevating him to co-emperor, giving him the title
Augustus.
Summer:
Carausius, commander of the Classis Britannica, is accused of
piracy by Maximian and is sentenced to death. He responds by declaring himself emperor of
Britain and Northwestern Gaul. His forces consist of the newly built
Roman fleet and three
legions in Britain. The
Carausian Revolt is supported by Gaulish merchant ships and
Frankish mercenaries.
On the same day that he is made
consul,
Maximian launches a campaign against an invasion of Gaul by the
Alemanni. After defeating this invasion, he then invades Alemannia itself, entering across the Upper Rhine and returning to Roman territory via the Upper Danube.
Around this time, the future emperor
Constantius defeats and captures a Germanic king, the latter having prepared an ambush against the Romans.
Diocletian signs a peace treaty with King
Bahram II of
Persia, and installs the pro-Roman Arsacid
Tiridates III as king over the western portion of
Armenia.
Diocletian re-organizes the
Mesopotamian frontier, and fortifies various locations including the city of
Circesium (modern
Busayrah) on the
Euphrates. Around this time, he begins the construction of the
Strata Diocletiana. Throughout his reign, similar fortification efforts are conducted on the other frontiers as well, with fortifications constructed or restored behind, on and beyond the borders. Conscription and the number of legions increase, although the legions themselves are reformed into smaller and more flexible units. At some point in time, Diocletian may have also established the late Roman military system of
Comitatenses (field army units) and
Limitanei (border units), but some scholars date this development to the reign of
Constantine I (r. 306–337).
Around this time, an army loyal to
Maximian, probably led by the future emperor
Constantius, defeats the usurper
Carausius or his
Frankish allies in northern
Gaul. In this or the following year, Carausius withdraws his military forces and administrative presence from Gaul, confining himself to
Roman Britain.
Maximian makes an alliance with the Frankish king Gennobaudes.
Far from Carausius' fleet, in the rivers of Gaul, Maximian builds a fleet to contest control of the
North Sea and re-take Britain.
Around this time, Constantius marries Maximian's stepdaughter,
Theodora, and it may also be around this time that the general
Galerius marries Diocletian's daughter
Galeria Valeria.
In this or the following year, Emperor
Diocletian campaigns with success against the
Sarmatians. The future emperor
Galerius may have distinguished himself during this campaign. [12]
In this or the following year,
Maximian attempts to reconquer
Britain from the usurper
Carausius but is defeated at sea. [13]
Significant people
This section is empty. You can help by
adding to it. (March 2016)
^Hornblower, Simon (9 November 2023).
"Ancient Rome". Britannica. Retrieved 11 November 2023.
^Lotha, Gloria (9 August 2020).
"Wudi". Britannica. Retrieved 11 November 2023.
^Yarshater, Ehsan; Fisher, William Bayne, eds. (1968). "Iran under the Sasanians". The Cambridge History of Iran. Vol. 3. Cambridge: Cambridge University Press. p. 128.
ISBN978-0-52106-935-9.
^Thomas, P. C. (1992), A Compact History of the Popes, Mumbai: Bombay Society of St Paul, p. 19,
ISBN978-8-17109-142-3
^Cousin, Jean.
"Diocletian". Encyclopædia Britannica. Retrieved February 23, 2024.
^ According to Yu Liang's biography in Book of Jin, he was 52 (by East Asian reckoning) when he died. (咸康六年薨,时年五十二。) Jin Shu, vol.73. Thus by calculation, his birth year should be 289.
Probus defeats the army under Bonosus. Bonosus sees no way out and
hangs himself. His family is treated with
honours.[2]
Julius Saturninus, governor of
Syria, is in
Alexandria, charged with the defense of the East. He is declared emperor and withdraws to
Apamea. Probus besieges the city and puts him to death.[3]
Roman territory is under constant threat of raids from
Franks. The cities in Gaul are reinforced with
defensive walls.[4]
Emperor Wu of the
Jin dynasty completes the unification of China, which was previously divided between three contending powers during the
Three Kingdoms period. The Jin dynasty's capital of
Luoyang becomes a thriving centre of commerce as foreign diplomats and traders travel there.[5]
The praetorian prefect
Marcus Aurelius Carus usurps power in
Raetia. Probus attempts to organise a campaign against Carus but is murdered by his discontented troops in
Sirmium.
Carus defeats the
Quadi and
Sarmatians on the
Danube; for his victories he is given the title Germanicus Maximus.
Exploiting the Persian civil war, Carus leaves Carinus in charge of much of the Roman Empire and, accompanied by his younger son Numerian, invades the
Sassanid Empire. They sack
Seleucia and
Ctesiphon, the capital of the
Persian kingdom, and they press on beyond the
Tigris. For his victories, Carus receives the title of Persicus Maximus.[citation needed]
The officer Diocles, the future Emperor
Diocletian, distinguishes himself in the war against the Persians.[citation needed]
Carinus campaigns with success in Britain and on the Rhine frontier.[citation needed]
Summer: Carus dies in mysterious circumstances during the war against the Persians. Various sources claim he died of illness, was struck by lightning or was killed in combat.[citation needed]
Carinus and
Numerian succeed their father Carus. Numerian, who had accompanied his father into the Persian Empire, leads the army back to Roman territory.[citation needed]
Emperor
Numerian travels through
Bithynia (
Asia Minor) on his way home to
Rome. Suffering from an
inflammation of the eyes, he travels in a closed
litter in which soldiers find his decaying corpse.
November 20 – The commander of Numerian's
domestici (household troops),
Diocles, is chosen to be the new emperor. In a military assembly outside
Nicomedia (modern
İzmit, Turkey), Diocles claims that the praetorian prefect (and rival for the throne) Arrius Aper murdered Numerian, and he personally stabs and kills the prefect on the spot. The new emperor changes his name to the Latinised 'Diocletian'. Building on existing trends, Diocletian presents his rule as that of a god-like
dominus or autocrat.
Sabinus Julianus, the praetorian prefect of Emperor
Carinus, exploits the instability and usurps the throne in northern Italy.
Persian Empire
King of Kings
Bahram II installs
Mirian III, of the House of Mihran, on the throne of the
Kingdom of Iberia. Mirian would rule the kingdom until his death in c. 361.
Korea
Yurye becomes king of the Korean kingdom of
Silla.[9]
Summer –
Battle of the Margus: Emperor
Diocletian defeats the forces of Carinus in the valley of the
Margus (
Serbia). Numerous soldiers desert Carinus during the battle. Carinus then flees to the Pannonian fort of Cornacum, but he is soon slain by his officers.
July 21 or
July 25 – Diocletian appoints his fellow-officer
Maximian to the office of
caesar, or junior co-emperor.
Winter/Spring: The CaesarMaximian defeats the Bagaudae rebellion in Gaul. He then defeats a Germanic invasion into Gaul, defeating an army of
Burgundians and
Alemanni and another army of Chaibones and
Heruli.
Emperor
Diocletian campaigns successfully against
Sarmatian raids. The future emperor
Constantius defeats the 'Bosporian Sarmatians'.
April 1 – Diocletian rewards Maximian by elevating him to co-emperor, giving him the title
Augustus.
Summer:
Carausius, commander of the Classis Britannica, is accused of
piracy by Maximian and is sentenced to death. He responds by declaring himself emperor of
Britain and Northwestern Gaul. His forces consist of the newly built
Roman fleet and three
legions in Britain. The
Carausian Revolt is supported by Gaulish merchant ships and
Frankish mercenaries.
On the same day that he is made
consul,
Maximian launches a campaign against an invasion of Gaul by the
Alemanni. After defeating this invasion, he then invades Alemannia itself, entering across the Upper Rhine and returning to Roman territory via the Upper Danube.
Around this time, the future emperor
Constantius defeats and captures a Germanic king, the latter having prepared an ambush against the Romans.
Diocletian signs a peace treaty with King
Bahram II of
Persia, and installs the pro-Roman Arsacid
Tiridates III as king over the western portion of
Armenia.
Diocletian re-organizes the
Mesopotamian frontier, and fortifies various locations including the city of
Circesium (modern
Busayrah) on the
Euphrates. Around this time, he begins the construction of the
Strata Diocletiana. Throughout his reign, similar fortification efforts are conducted on the other frontiers as well, with fortifications constructed or restored behind, on and beyond the borders. Conscription and the number of legions increase, although the legions themselves are reformed into smaller and more flexible units. At some point in time, Diocletian may have also established the late Roman military system of
Comitatenses (field army units) and
Limitanei (border units), but some scholars date this development to the reign of
Constantine I (r. 306–337).
Around this time, an army loyal to
Maximian, probably led by the future emperor
Constantius, defeats the usurper
Carausius or his
Frankish allies in northern
Gaul. In this or the following year, Carausius withdraws his military forces and administrative presence from Gaul, confining himself to
Roman Britain.
Maximian makes an alliance with the Frankish king Gennobaudes.
Far from Carausius' fleet, in the rivers of Gaul, Maximian builds a fleet to contest control of the
North Sea and re-take Britain.
Around this time, Constantius marries Maximian's stepdaughter,
Theodora, and it may also be around this time that the general
Galerius marries Diocletian's daughter
Galeria Valeria.
In this or the following year, Emperor
Diocletian campaigns with success against the
Sarmatians. The future emperor
Galerius may have distinguished himself during this campaign. [12]
In this or the following year,
Maximian attempts to reconquer
Britain from the usurper
Carausius but is defeated at sea. [13]
Significant people
This section is empty. You can help by
adding to it. (March 2016)
^Hornblower, Simon (9 November 2023).
"Ancient Rome". Britannica. Retrieved 11 November 2023.
^Lotha, Gloria (9 August 2020).
"Wudi". Britannica. Retrieved 11 November 2023.
^Yarshater, Ehsan; Fisher, William Bayne, eds. (1968). "Iran under the Sasanians". The Cambridge History of Iran. Vol. 3. Cambridge: Cambridge University Press. p. 128.
ISBN978-0-52106-935-9.
^Thomas, P. C. (1992), A Compact History of the Popes, Mumbai: Bombay Society of St Paul, p. 19,
ISBN978-8-17109-142-3
^Cousin, Jean.
"Diocletian". Encyclopædia Britannica. Retrieved February 23, 2024.
^ According to Yu Liang's biography in Book of Jin, he was 52 (by East Asian reckoning) when he died. (咸康六年薨,时年五十二。) Jin Shu, vol.73. Thus by calculation, his birth year should be 289.