Emperor
Diocletian campaigns with success against Arabic enemies.
Following his victory over Emperor
Maximian's fleet, the usurper
Carausius invades the European mainland and re-establishes his military and administrative presence in northern Gaul.
Asia
May 16 – Emperor
Wu of Jin, founder of the
Western Jin Dynasty, dies after a 25-year reign. He reunifies north and south, but gives away many
dukedoms to his kinsmen. Crown Prince
Sima Zhong succeeds his father, and has to deal with conflicts among the
aristocratic families in
China.
An uneasy peace is established between the emperors Diocletian and Maximian on the one hand, and the rival emperor
Carausius on the other.
Perhaps in cooperation with the forces of Maximian, Carausius campaigns successfully against Germanic raids in Gaul and Britain. Also during his reign, Carausius begins building the forts of the
Saxon Shore.
Northern Europe
The
Alemanni, having been expelled from part of their territory by the
Burgundians, seek to regain their lost lands. These peoples had unsuccessfully invaded
Gaul in tandem in 285/6, and the Alemanni had likely been weakened by the Roman counter-invasions of 287 and 288.
King
Bahram II fights against a coalition consisting of his brother
Hormizd of Sakastan, Sassanian vassal Hormizd I Kushashah, and the Gilans.
China
War of the Eight Princes: After the death of Emperor
Sima Yan (Jin Wudi), a civil war breaks out among the princes and
dukes of the
Jin Dynasty. The struggle devastates and depopulates the provinces of northern
China.
March 1 – Emperors
Diocletian and
Maximian appoint
Constantius I and
Galerius as
Caesars. This is considered the beginning of the
Tetrarchy, known as the Quattuor Principes Mundi ("Four Rulers of the World"). (Some sources and scholars date Galerius' elevation to
May 21.)
Constantius retakes some of the
Gallic territories from the usurper
Carausius. He conquers the crucial port of
Bononia (modern
Boulogne).
Towards the end of the year, Carausius is murdered by his finance minister
Allectus, who proclaims himself the new emperor of
Britain.
Galerius begins a series of two campaigns in Upper Egypt against the rebel cities of
Coptos and Boresis as well as the
Blemmyes and
Meroitic Nubians.
Over the course of his reign, but especially from the time of the Tetrarchy's creation, Diocletian divides the large provinces of the early empire into smaller administrative units, and he groups these new smaller provinces into
dioceses. He also accelerates the third-century trend whereby the administration and military of the provinces are increasingly divided between governors and generals (duces) respectively, whereas formerly governors had also been in charge of the legions. This expansion of imperial personnel increases Diocletian's control over the empire and weakens the power of individual officials and officers. Moreover, Diocletian expands the retinues of the individual emperors to have more ministers and secretaries, thus establishing what will become known as the late Roman
Consistorium.
Persia
King
Bahram II of the
Persian Empire dies after a 17-year reign; his son
Bahram III ascends to the throne. After four months, Bahram III's great-uncle
Narseh, the king of
Persarmenia, marches on the Persian capital
Ctesiphon with the support of a faction of the nobility and the eastern Satraps. Bahram is overthrown and Narseh is declared the new King of Kings.
Caesar
Galerius completes a series of two campaigns in Upper Egypt, against the rebel cities of
Coptos and Boresis, as well as the
Blemmyes and
Meroitic Nubians.
In this or the previous year, Caesar
Constantius I assembles two invasion fleets with the intent of overthrowing the usurper
Allectus, who is based in Britain. The first is under the command of
Asclepiodotus,
Maximian's long-serving
Praetorian Prefect. Asclepiodotus sails from the mouth of the
Seine, and lands near the
Isle of Wight, where his forces defeat Allectus in
Hampshire. Allectus is killed in the fighting. Constantius leaves
Boulogne with his fleet, and occupies
London, where he slaughters some of Allectus'
Frankish mercenaries. With this victory, the Romano-British regime first established by
Carausius is overthrown, and Britain is re-incorporated into the rest of the empire.
Having supervised the Rhine frontier during Constantius' invasion of Britain, Maximian then marches into Spain, where he fights
Frankish pirates. He then crosses into North Africa to contend with the rebellion of the
Quinquegentiani.
The Persian king
Narseh invades Roman-held Upper Mesopotamia and
Arsacid western
Armenia, the latter territory being under the leadership of the pro-Roman king
Tiridates III. With only a small army, Caesar
Galerius fights three holding actions against Narseh's army in Mesopotamia. Somewhere in the open plains between
Carrhae and
Callinicum, Galerius' army suffers a defeat against the Persian army, which is both more numerous and contains superior numbers of high-quality cavalry. Nevertheless, Galerius succeeds in blunting the Persian offensive.
Emperor
Diocletian introduces a new tax system and other economic reforms.[4]
Diocletian watches over the Syrian provinces while Caesar
Galerius makes preparations for a campaign against the Persian king
Narseh. He recruits veterans from
Illyria and
Moesia, recruits new soldiers, and strengthens his army with
Gothic mercenaries and the
Armenian units of
Tiridates III.
August:
Domitius Domitianus launches a usurpation against Diocletian in Egypt. He is perhaps aided by popular discontent with Diocletian's taxation reform.
Autumn: Diocletian besieges the rebels in
Alexandria.
December: Domitianus dies, but his correctorAurelius Achilleus takes over as the leader of the rebellion.
Battle of Satala: Galerius launches a surprise attack against Narseh's camp in western
Armenia. The Romans sack the camp and capture Narseh's wives, sisters and daughters, including his Queen of Queens Arsane. Narseh is wounded and escapes to his empire.
Diocletian then travels into Upper Egypt and possibly campaigns on the Nubian frontier. In either this year or in 300/301, he makes agreements with the
Meroitic Nubians and the
Blemmyes. He agrees to pay subsidies to both peoples, and he cedes the Dodecashoenos to the Nubians on the understanding that the Nubians will defend the region against the Blemmyes.
Peace of Nisibis: Emperor
Diocletian signs a treaty with the Persian king
Narseh that will last for 40 years. The Persians accept Roman dominion over
Armenia, the
Caucasus, and Upper
Mesopotamia. The pro-Roman ruler
Tiridates III receives all of Armenia as far as the border with
Atropatene.
Mirian III of the
Kingdom of Iberia is made a Roman client, and at some point in time, as a result of the treaty,
Caucasian Albania will follow suit. Rome also gains five satrapies beyond the Tigris, which are perhaps given to Tiridates to administer.
In this or the following year, Galerius campaigns with success against
Sarmatians and the
Marcomanni, attacking through a swamp to defeat a Sarmatian army.
Having first crossed into Africa in 296, Emperor
Maximian concludes his campaigns against the
Quinquegentiani and other
Berbers. His campaigns had ranged as far as
Mauretania in the west and
Tripolitania in the east. Julianus, a rebel leader in Africa, throws himself into a fire after the Romans breach the walls of his stronghold.
Returning to Rome in triumph, Maximian commissions the
Baths of Diocletian in honour of his 'brother' Diocletian.
Emperor
Diocletian campaigns with success against Arabic enemies.
Following his victory over Emperor
Maximian's fleet, the usurper
Carausius invades the European mainland and re-establishes his military and administrative presence in northern Gaul.
Asia
May 16 – Emperor
Wu of Jin, founder of the
Western Jin Dynasty, dies after a 25-year reign. He reunifies north and south, but gives away many
dukedoms to his kinsmen. Crown Prince
Sima Zhong succeeds his father, and has to deal with conflicts among the
aristocratic families in
China.
An uneasy peace is established between the emperors Diocletian and Maximian on the one hand, and the rival emperor
Carausius on the other.
Perhaps in cooperation with the forces of Maximian, Carausius campaigns successfully against Germanic raids in Gaul and Britain. Also during his reign, Carausius begins building the forts of the
Saxon Shore.
Northern Europe
The
Alemanni, having been expelled from part of their territory by the
Burgundians, seek to regain their lost lands. These peoples had unsuccessfully invaded
Gaul in tandem in 285/6, and the Alemanni had likely been weakened by the Roman counter-invasions of 287 and 288.
King
Bahram II fights against a coalition consisting of his brother
Hormizd of Sakastan, Sassanian vassal Hormizd I Kushashah, and the Gilans.
China
War of the Eight Princes: After the death of Emperor
Sima Yan (Jin Wudi), a civil war breaks out among the princes and
dukes of the
Jin Dynasty. The struggle devastates and depopulates the provinces of northern
China.
March 1 – Emperors
Diocletian and
Maximian appoint
Constantius I and
Galerius as
Caesars. This is considered the beginning of the
Tetrarchy, known as the Quattuor Principes Mundi ("Four Rulers of the World"). (Some sources and scholars date Galerius' elevation to
May 21.)
Constantius retakes some of the
Gallic territories from the usurper
Carausius. He conquers the crucial port of
Bononia (modern
Boulogne).
Towards the end of the year, Carausius is murdered by his finance minister
Allectus, who proclaims himself the new emperor of
Britain.
Galerius begins a series of two campaigns in Upper Egypt against the rebel cities of
Coptos and Boresis as well as the
Blemmyes and
Meroitic Nubians.
Over the course of his reign, but especially from the time of the Tetrarchy's creation, Diocletian divides the large provinces of the early empire into smaller administrative units, and he groups these new smaller provinces into
dioceses. He also accelerates the third-century trend whereby the administration and military of the provinces are increasingly divided between governors and generals (duces) respectively, whereas formerly governors had also been in charge of the legions. This expansion of imperial personnel increases Diocletian's control over the empire and weakens the power of individual officials and officers. Moreover, Diocletian expands the retinues of the individual emperors to have more ministers and secretaries, thus establishing what will become known as the late Roman
Consistorium.
Persia
King
Bahram II of the
Persian Empire dies after a 17-year reign; his son
Bahram III ascends to the throne. After four months, Bahram III's great-uncle
Narseh, the king of
Persarmenia, marches on the Persian capital
Ctesiphon with the support of a faction of the nobility and the eastern Satraps. Bahram is overthrown and Narseh is declared the new King of Kings.
Caesar
Galerius completes a series of two campaigns in Upper Egypt, against the rebel cities of
Coptos and Boresis, as well as the
Blemmyes and
Meroitic Nubians.
In this or the previous year, Caesar
Constantius I assembles two invasion fleets with the intent of overthrowing the usurper
Allectus, who is based in Britain. The first is under the command of
Asclepiodotus,
Maximian's long-serving
Praetorian Prefect. Asclepiodotus sails from the mouth of the
Seine, and lands near the
Isle of Wight, where his forces defeat Allectus in
Hampshire. Allectus is killed in the fighting. Constantius leaves
Boulogne with his fleet, and occupies
London, where he slaughters some of Allectus'
Frankish mercenaries. With this victory, the Romano-British regime first established by
Carausius is overthrown, and Britain is re-incorporated into the rest of the empire.
Having supervised the Rhine frontier during Constantius' invasion of Britain, Maximian then marches into Spain, where he fights
Frankish pirates. He then crosses into North Africa to contend with the rebellion of the
Quinquegentiani.
The Persian king
Narseh invades Roman-held Upper Mesopotamia and
Arsacid western
Armenia, the latter territory being under the leadership of the pro-Roman king
Tiridates III. With only a small army, Caesar
Galerius fights three holding actions against Narseh's army in Mesopotamia. Somewhere in the open plains between
Carrhae and
Callinicum, Galerius' army suffers a defeat against the Persian army, which is both more numerous and contains superior numbers of high-quality cavalry. Nevertheless, Galerius succeeds in blunting the Persian offensive.
Emperor
Diocletian introduces a new tax system and other economic reforms.[4]
Diocletian watches over the Syrian provinces while Caesar
Galerius makes preparations for a campaign against the Persian king
Narseh. He recruits veterans from
Illyria and
Moesia, recruits new soldiers, and strengthens his army with
Gothic mercenaries and the
Armenian units of
Tiridates III.
August:
Domitius Domitianus launches a usurpation against Diocletian in Egypt. He is perhaps aided by popular discontent with Diocletian's taxation reform.
Autumn: Diocletian besieges the rebels in
Alexandria.
December: Domitianus dies, but his correctorAurelius Achilleus takes over as the leader of the rebellion.
Battle of Satala: Galerius launches a surprise attack against Narseh's camp in western
Armenia. The Romans sack the camp and capture Narseh's wives, sisters and daughters, including his Queen of Queens Arsane. Narseh is wounded and escapes to his empire.
Diocletian then travels into Upper Egypt and possibly campaigns on the Nubian frontier. In either this year or in 300/301, he makes agreements with the
Meroitic Nubians and the
Blemmyes. He agrees to pay subsidies to both peoples, and he cedes the Dodecashoenos to the Nubians on the understanding that the Nubians will defend the region against the Blemmyes.
Peace of Nisibis: Emperor
Diocletian signs a treaty with the Persian king
Narseh that will last for 40 years. The Persians accept Roman dominion over
Armenia, the
Caucasus, and Upper
Mesopotamia. The pro-Roman ruler
Tiridates III receives all of Armenia as far as the border with
Atropatene.
Mirian III of the
Kingdom of Iberia is made a Roman client, and at some point in time, as a result of the treaty,
Caucasian Albania will follow suit. Rome also gains five satrapies beyond the Tigris, which are perhaps given to Tiridates to administer.
In this or the following year, Galerius campaigns with success against
Sarmatians and the
Marcomanni, attacking through a swamp to defeat a Sarmatian army.
Having first crossed into Africa in 296, Emperor
Maximian concludes his campaigns against the
Quinquegentiani and other
Berbers. His campaigns had ranged as far as
Mauretania in the west and
Tripolitania in the east. Julianus, a rebel leader in Africa, throws himself into a fire after the Romans breach the walls of his stronghold.
Returning to Rome in triumph, Maximian commissions the
Baths of Diocletian in honour of his 'brother' Diocletian.