Editing Tetrarchy (section)

==Detailed timeline==
{| width=50% class="wikitable" style="text-align:center"
|-
! colspan="4" |<big>Diarchy</big><br />1 April 286 – 1 March 293
|-
! colspan="2" |[[Western Roman Empire]]
! colspan="2" |[[Eastern Roman Empire]]
|-
|[[File:MSR - Tête de l'empreur Maximien Hercule - Inv 34 b (cropped).jpg|133x133px]]
| '''[[Maximian|Maximian Augustus]]'''
|[[File:Istanbul - Museo archeol. - Diocleziano (284-305 d.C.) - Foto G. Dall'Orto 28-5-2006 (cropped).jpg|100px]]
| '''[[Diocletian|Diocletian Augustus]]'''
|-
! colspan="4" |Usurpers
|-
|[[File:Aureus Carausius RIC 0005 (obverse).jpg|100px]]
| [[Carausius]]<br/>{{small|in [[Roman Britain|Britain]] (286–293)}}
| colspan="2" |—
|}
Two ''caesares'' are appointed in 293, thus starting the Tetrarchy.
{| class="wikitable" width="50%" style="text-align:center"
|-
! colspan="4" |<big>First Tetrarchy</big><br />1 March 293 – 1 May 305
|-
! colspan="2" |[[Western Roman Empire]]
! colspan="2" |[[Eastern Roman Empire]]
|-
|[[File:MSR - Tête de l'empreur Maximien Hercule - Inv 34 b (cropped).jpg|133x133px]]
| '''[[Maximian|Maximian Augustus]]'''
|[[File:Istanbul - Museo archeol. - Diocleziano (284-305 d.C.) - Foto G. Dall'Orto 28-5-2006 (cropped).jpg|100px]]
| '''[[Diocletian|Diocletian Augustus]]'''
|-
|[[File:Constantius Chlorus Ny Carlsberg Glyptotek IN836 (cropped).jpg|141x141px]]
| [[Constantius Chlorus|Constantius Caesar]]
|[[File:Romuliana Galerius head.jpg|140x140px]]
|[[Galerius|Galerius Caesar]]
|-
! colspan="4" |Usurpers
|-
|[[File:Aureus Carausius RIC 0005 (obverse).jpg|100px]]
|[[Carausius]]<br />{{small|in [[Roman Britain|Britain]] (286–293)}}
|[[File:Nummus Domitius Domitianus (obverse).jpg|105x105px]]
|[[Domitian III]]<br />{{small|in [[Roman Egypt|Egypt]] (297)}}
|-
|[[File:Aureus Allectus RIC 0001 (obverse).jpg|100x100px]]
|[[Allectus]]<br />{{small|in [[Roman Britain|Britain]] (293–296)}}
|[[File:Aschils.jpg|92x92px]]
|[[Aurelius Achilleus|Achilleus]]<br />{{small|in [[Roman Egypt|Egypt]] (297–298)}}
|}
After the retirement of the two a''ugusti'' both previous ''caesares'' succeeded them, and two new ''caesares'' were appointed.
{| class="wikitable" width="50%" style="text-align:center"
|-
! colspan="4" |<big>Second Tetrarchy</big><br />1 May 305 – 25 July 306
|-
! colspan="2" |[[Western Roman Empire]]
! colspan="2" |[[Eastern Roman Empire]]
|-
|[[File:Constantius Chlorus Ny Carlsberg Glyptotek IN836 (cropped).jpg|141x141px]]
| '''[[Constantius Chlorus|Constantius Augustus]]'''
|[[File:Romuliana Galerius head.jpg|137x137px]]
| '''[[Galerius|Galerius Augustus]]'''
|-
|[[File:Gold Aureus of Severus II (MANTIS).jpg|100x100px]]
|[[Severus II|Severus Caesar]]
|[[File:Maximinus Caesar (obverse).jpg|100x100px]]
|[[Maximinus Daza|Maximinus Caesar]]
|}
After the sudden death of [[Constantius Chlorus]] (who died of natural causes), the ''caesar'' [[Flavius Severus]] succeeded him as ''augustus''. However, Constantius' troops immediately proclaimed Constantine, Constantius' son, as their new ''augustus''. Galerius accepted Constantine as part of the imperial college, but only as ''caesar''. On 28 October 306, Maximian's son [[Maxentius]] proclaimed himself emperor in Rome. Maximian also proclaimed himself emperor, ruling jointly with his son. Despite being accepted by the [[Roman Senate]], they were not recognized by the other emperors.{{sfn|Barnes|1984|pp=30–33}}
{| class="wikitable" width="50%" style="text-align:center"
|-
! colspan="4" |<big>Third Tetrarchy</big><br />25 July 306 – September 307
|-
! colspan="2" |[[Western Roman Empire]]
! colspan="2" |[[Eastern Roman Empire]]
|-
|[[File:Severus II Aureus Joanneum.jpg|100x100px]]
| '''[[Severus II|Severus Augustus]]'''
|[[File:Romuliana Galerius head.jpg|137x137px]]
| '''[[Galerius|Galerius Augustus]]'''
|-
|[[File:Head Constantine Musei Capitolini MC1072 (cropped).jpg|133x133px]]
|[[Constantine the Great|Constantine Caesar]]<br />{{small|(self-styled ''augustus'')}}
|[[File:Maximinus Caesar (obverse).jpg|100x100px]]
|[[Maximinus Daza|Maximinus Caesar]]
|-
! colspan="4" |Usurpers
|-
| [[File:Head of Maxentius from Dresden Colosseum Rome Italy (cropped).jpg|137x137px]]
|[[Maxentius]]<br />{{small|in Italy and Africa<br/>(from 28 October 306)}}
|[[File:MSR - Tête de l'empreur Maximien Hercule - Inv 34 b (cropped).jpg|133x133px]]
|[[Maximian]]<br />{{small|in Italy and Africa<br/>(from 28 October 306)}}
|}
Severus was taken hostage by Maximian in April 307, but Galerius still acknowledged him as the official emperor of the west. Constantine was denied the promotion to ''augustus'' even after Severus' death in September, as Galerius had decided to exclude him from the system altogether. Maximian acknowledge Constantine's status as ''augustus'', but this meant nothing given that he himself was declared an usurper. Galerius and Maximinus thus remained as the only "legimitate" members of the imperial college.{{sfn|Barnes|1984|pp=30–33}}
{| class="wikitable" width="50%" style="text-align:center"
|-
! colspan="4" |<big>Galerius as sole Augustus</big><br />September 307 – November 308
|-
! colspan="2" |[[Western Roman Empire]]
! colspan="2" |[[Eastern Roman Empire]]
|-
| colspan="2" rowspan="2" |('''vacant''')
|[[File:Romuliana Galerius head.jpg|137x137px]]
| '''[[Galerius|Galerius Augustus]]'''
|-
|[[File:Maximinus Caesar (obverse).jpg|100x100px]]
|[[Maximinus Daza|Maximinus Caesar]]
|-
! colspan="4" |Usurpers
|-
| [[File:Head of Maxentius from Dresden Colosseum Rome Italy (cropped).jpg|137x137px]]
|[[Maxentius]]<br />{{small|in Italy and Africa}}
|[[File:MSR - Tête de l'empreur Maximien Hercule - Inv 34 b (cropped).jpg|133x133px]]
|[[Maximian]]<br />{{small|in Italy and Africa}}
|-
|[[File:Head Constantine Musei Capitolini MC1072 (cropped).jpg|137x137px]]
|[[Constantine the Great|Constantine]]<br />{{small|in [[Gaul]] and [[Hispania]]}}
| colspan="2" |
|}
At the council of Carnutum, Diocletian decides that Licinius will be the new ''augustus'' of the west (although his western domains only consist of the [[Diocese of Pannonia]]). Constantine was given back the title of ''caesar'', which he continued to unacknowledge.{{sfn|Barnes|1984|pp=30–33}}
{| class="wikitable" width="50%" style="text-align:center"
|-
! colspan="4" |<big>Fourth Tetrarchy</big><br />11 November 308 – May 310
|-
! colspan="2" |[[Western Roman Empire]]
! colspan="2" |[[Eastern Roman Empire]]
|-
|[[File:Bust of Licinius, Kunsthistorisches Museum (cropped).jpg|137x137px]]
| [[Licinius|'''Licinius Augustus''']]
|[[File:Romuliana Galerius head.jpg|137x137px]]
| '''[[Galerius|Galerius Augustus]]'''
|-
|[[File:Head Constantine Musei Capitolini MC1072 (cropped).jpg|137x137px]]
|[[Constantine the Great|Constantine Caesar]]<br />{{small|(self-styled ''augustus'')}}
|[[File:Maximinus Caesar (obverse).jpg|100x100px]]
|[[Maximinus Daza|Maximinus Caesar]]
|-
! colspan="4" |Usurpers
|-
| [[File:Head of Maxentius from Dresden Colosseum Rome Italy (cropped).jpg|137x137px]]
|[[Maxentius]]<br />{{small|in [[Roman Italy|Italy]]}}
|[[File:Alexander of Carthage follis (obverse).png|100x100px]]
|[[Domitius Alexander]]<br />{{small|in [[Africa (Roman province)|Africa]] (308–310?)}}
|}
Maximinus was proclaimed ''augustus'' by his troops in about May 310. Galerius reluctantly agreed to recognize both Maximinus and Constantine as ''augusti'', thus breaking the Diocletian's tetrarchic system.{{sfn|Barnes|1984|pp=30–33}}
{| class="wikitable" width="50%" style="text-align:center"
|-
! colspan="4" |<big>Tetrarchy of Augusti</big><br />May 310 – May 311
|-
! colspan="2" |[[Western Roman Empire]]
! colspan="2" |[[Eastern Roman Empire]]
|-
|[[File:Bust of Licinius, Kunsthistorisches Museum (cropped).jpg|137x137px]]
| [[Licinius|'''Licinius Augustus''']]
|[[File:Romuliana Galerius head.jpg|137x137px]]
| '''[[Galerius|Galerius Augustus]]'''
|-
|[[File:Head Constantine Musei Capitolini MC1072 (cropped).jpg|137x137px]]
|'''[[Constantine the Great|Constantine Augustus]]'''
|[[File:Gold Aureus of Maximinus Daia, Alexandria, AD 311 - AD 313.jpg|100x100px]]
|[[Maximinus Daza|'''Maximinus Augustus''']]
|-
! colspan="4" |Usurpers
|-
| [[File:Head of Maxentius from Dresden Colosseum Rome Italy (cropped).jpg|137x137px]]
|[[Maxentius]]<br />{{small|In Italy and Africa}}
|[[File:MSR - Tête de l'empreur Maximien Hercule - Inv 34 b (cropped).jpg|133x133px]]
|[[Maximian]]<br />{{small|In Gaul, {{circa}} July 310}}
|}
After the death of Galerius' (who died of natural causes), Licinius acquires parts of his domains, thus ruling over territories both in the East and West.
{| class="wikitable" width="50%" style="text-align:center"
|-
! colspan="4" |<big>Tetrarchy of Augusti</big><br />May 311 – August 313
|-
! colspan="2" |[[Western Roman Empire]]
! colspan="2" |[[Eastern Roman Empire]]
|-
|[[File:Bust of Licinius, Kunsthistorisches Museum (cropped).jpg|137x137px]]
| [[Licinius|'''Licinius Augustus''']]
| colspan="2" |('''Licinius''')
|-
|[[File:Head Constantine Musei Capitolini MC1072 (cropped).jpg|137x137px]]
|'''[[Constantine the Great|Constantine Augustus]]'''
|[[File:Gold Aureus of Maximinus Daia, Alexandria, AD 311 - AD 313.jpg|100x100px]]
|'''[[Maximinus Daza|Maximinus Augustus]]'''
|-
! colspan="4" |Usurpers
|-
| [[File:Head of Maxentius from Dresden Colosseum Rome Italy (cropped).jpg|137x137px]]
|[[Maxentius]]<br />{{small|In Italy and Africa<br/>(until 28 October 312)}}
| colspan="2" |—
|}
Licinius eventually fights and defeats Maximinus, gaining all eastern territories. He then makes peace with Constantine, who remains as the emperor of the West. This joint rule lasted until 316, when Licinius rejected Constantine's election of [[Bassianus (executed by Constantine)|Bassianus]] as ''caesar''. In the ensuing war, both ''augusti'' appointed their own sons as ''caesares'', restoring a dynastic system. Licinius appointed [[Valerius Valens|Valens]] and [[Martinian (emperor)|Martinian]] as ''augustus'' in 316 and 324 respectively (literary sources refer to them as ''caesar'', but coins bear the title ''augustus''); almost nothing is known about them.
{| class="wikitable" width="50%" style="text-align:center"
|-
! colspan="4" |<big>New Diarchy</big><br />August 313 – 18 September 324
|-
! colspan="2" |[[Western Roman Empire]]
! colspan="2" |[[Eastern Roman Empire]]
|-
|[[File:Head Constantine Musei Capitolini MC1072 (cropped).jpg|137x137px]]
| '''[[Constantine the Great|Constantine Augustus]]'''
|[[File:Bust of Licinius, Kunsthistorisches Museum (cropped).jpg|137x137px]]
|[[Licinius|'''Licinius Augustus''']]
|-
|[[File:INC-1822-a Солид Крисп цезарь ок. 317 г. (аверс).png|100x100px]]
|[[Crispus|Crispus Caesar]]<br />{{small|from 317}}
|[[File:Valerius Valens coin (transparent background).png|100x100px]]
|'''[[Valerius Valens|Valens Augustus]]'''<br />{{small|in 316}}{{efn|Nominal emperor of the West.}}
|-
|[[File:INC-2046-a Ауреус. Константин II. Ок. 337—340 гг. (аверс).png|100x100px]]
|[[Constantine II (emperor)|Constantine Caesar]]<br />{{small|from 317}}
|[[File:Martinian coin (transparent background).png|100x100px]]
|'''[[Martinian (emperor)|Martinian Augustus]]'''<br />{{small|in 324}}{{efn|Nominal emperor of the West.}}
|-
| colspan="2" |—
|[[File:Solidus Licinius Jr AF21 CdM Paris.jpg|100x100px]]
|[[Licinius II|Licinius Caesar]]<br />{{small|from 317}}
|}