27 BCE The Senate confers on Octavian the title of Augustus
23 BCE The Senate grants Augustus the powers of imperium proconsulare maius and tribunicia potestas for life, thereby ending the Roman Republic
9 CE Tiberius ends the Pannonian Revolt
9 CE Roman army under Varus annihilated in the Teutoburg Wald
14–37 CE Tiberius becomes emperor
14–16 CE Germanicus campaigns in Germany
37–41 CE Caligula becomes emperor
39–40 CE Caligula launches an abortive campaign against Germania and Britain
41–54 CE Claudius becomes emperor
43–44 CE Britain brought under Roman rule
68–69 CE Year of the Four Emperors
69–79 CE Vespasian becomes emperor; start of the Flavian dynasty
79–81 CE Titus becomes emperor
81–96 CE Domitian becomes emperor
96 CE Domitian murdered; Nerva becomes emperor
101 CE Trajan campaigns on the Danube
114–117 CE War with Parthia adds Armenia, Mesopotamia, and Assyria as new provinces
117 CE Hadrian becomes emperor and makes peace with Parthia
138–161 CE Antoninus Pius becomes emperor
161 CE Death of Antoninus; Marcus Aurelius becomes emperor with Verus as co-emperor
166 CE Start of the Antonine Plague
167–175 CE First Marcomannic War on the Danube
167 CE Marcus Aurelius attacks the Quadi
168 CE Marcus Aurelius becomes sole emperor
169–179 CE Marcus Aurelius campaigns in Pannonia
175 CE Avidius Cassius revolts
175–180 CE Second war on the tribes along the Danube
180 CE Commodus becomes emperor and makes peace with the Danubian tribes
193–194 CE A second Year of Four Emperors
193–211 CE Septimius Severus becomes emperor, starting the Severan dynasty
208–211 CE Septimius Severus heads the campaign in Britain and dies there
211–217 CE Caracalla becomes emperor
212 CE Caracalla confers citizenship on all free men in the Empire
216 CE War breaks out again in Parthia
218–222 CE Elagabalus becomes emperor
222–235 CE Alexander Severus becomes emperor
224–241 CE Artaxerxes I reigns over a new Persian dynasty, the Sassanids
235–238 CE Gordianus I and II become co-emperors
238–244 CE Gordianus III becomes emperor
241–271 CE Sapor I becomes ruler of Persia
242–243 CE Victorious Roman campaigns against the Persians
244–249 CE Philip the Arab becomes emperor
248 CE Rome celebrates its millennium
248–251 CE Decius becomes emperor
251 CE Decius killed in battle by Goths
251–253 CE Trebonianus Gallus becomes emperor
253–260 CE Valerian and his son Gallienus become co-emperors
253 CE Persians invade and take Antioch
260 CE Valerian captured by Persians
260–268 CE Gallienus becomes sole emperor
260–272 CE Zenobia seizes most of the Eastern Empire and Egypt but is defeated by Aurelian
274 CE Postumus establishes a new empire in Gaul (261–268), ruled by Tetricus (270–274)
268–270 CE Claudius II (Gothicus) becomes emperor
270–275 CE Aurelian becomes emperor
276–282 CE Probus becomes emperor
282–283 CE Carus becomes emperor
283–285 CE Carinus becomes emperor
283 CE Carus campaigns in Persia
284–305 CE Diocletian and Maximian become co-emperors
293 CE Diocletian creates the tetrarchy with himself and Maximian as co-Augusti and Galerius and Constantius as co-Caesars
297 CE The Empire is divided administratively into twelve dioceses
301 CE The Edict of Maximum Prices is published
305 CE Diocletian and Maximian abdicate; Galerius and Constantius become co-Augusti
306 CE Constantine is declared co-Augustus after death of his father, Constantius
306 CE Maxentius, son of Maximian, revolts against Constantine
308 CE An imperial conference, held by Diocletian, starts a new round of civil wars
312 CE Constantine’s victory at Milvian Bridge give him control of Rome
313 CE Constantine and his eastern rival, Licinius, reconcile and become co-emperors
313 CE The co-emperors issue the Edict of Milan, ending the persecution of Christians
314 CE A ten-year series of civil wars erupts
324 CE Constantine becomes sole emperor
325 CE The Council of Nicaea makes Christianity the official religion of the Empire
326 CE Constantine makes Byzantium the Empire’s new capital and renames it Constantinople
337 CE The Empire is divided among Constantine’s three sons, Constantine II (Western), Constans (Middle), and Constantius (Eastern)
338 CE Constantius fights war against Persia’s Sapor II; first siege of Nisibis
340 CE Constans and Constantine II fight; Constantine II is killed at the Battle of Aquileia
344 CE Persian victory at Singara
346 CE Second unsuccessful siege of Nisibis by Sapor II
350 CE Third siege of Nisibis. Because of trouble on his other frontiers, Sapor II makes a truce with Constantius. A usurper, Magnentius, murders Constans and becomes emperor in the west
351 CE Magnentius defeated by Constantius II at the Battle of Mursa
352 CE Italy recovered; Magnentius in Gaul
353 CE Final defeat and death of Magnentius; Constantius becomes the Empire’s sole ruler
356 CE Julian dispatched as Caesar to Gaul, where he successfully fights the Alemanni, Quadi, and Sarmatians
359 CE Sapor II invades Mesopotamia; Constantius goes to the east
360 CE Julian and the Gallic army revolt
361 CE Constantius dies; Julian becomes emperor
363 CE Julian killed, and his army disastrously defeated by Persians; army proclaims Jovian emperor
364 CE Jovian dies; Valentinian becomes emperor in the west, leaving his brother Valens to rule in the east
368 CE War of Valens with Goths
369–377 CE Huns conquer the Ostrogoths
375 CE Valentinian dies, and Gratian now rules in the west
377 CE Valens allows Goths to settle on the south bank of the Danube in Moesia
378 CE Gratian defeats Alemanni; Visigoths revolt; Valens is killed at the disaster at Adrianople
380 CE Gratian replaces Valens with Theodosius
382 CE Theodosius makes a treaty with the Goths allowing them to stay within the Empire
394 CE Theodosius makes his son Honorius the western Augustus, with Stilicho as his military commander
395 CE Theodosius dies; Arcadius and Honorius become co-emperors
396 CE Alaric’s Visigoths overrun the Balkans
397 CE Alaric is militarily checked by Stilicho and is given Illyria in the terms of peace
402 CE Alaric invades Italy but is checked by Stilicho
403 CE Alaric retires after defeat at Pollentia; Ravenna becomes the imperial capital
405–406 CE Germans led by Radagaisus invade Italy
406–407 CE Alans, Sueves, and Vandals invade Gaul
407 CE Constantine II revolts and establishes the Gallic Empire
408 CE Honorius puts Stilicho to death; the youth Theodosius II succeeds Arcadius; Alaric invades Italy and makes Rome pay a ransom
409 CE Alaric proclaims Attalus emperor
410 CE Attalus deposed; Alaric sacks Rome
411 CE Athaulf succeeds Alaric as king of the Visigoths; Constantine III is crushed by Constantius, ending the Gallic Empire
412 CE Athaulf withdraws from Italy to Narbonne
417 CE Visigoths establish themselves in Aquitania
420 CE Ostrogoths settle in Pannonia
425 CE Honorius dies; Valentinian III becomes emperor
427 CE Revolt of Boniface in Africa
429 CE Boniface invites the Vandals, under Geiseric, to migrate from Spain to Africa
433 CE Aetius rises to power in Italy
434 CE Attila becomes king of the Huns
439 CE Geiseric takes Carthage, breaking the Roman tax spine
440 CE Geiseric invades Sicily
441 CE Attila crosses the Danube to attack Thrace
443 CE Attila makes peace with the Eastern Empire under Theodosius II; the Burgundians settle in Gaul
447 CE Attila invades the eastern provinces a second time
449 CE Attila makes a second peace in return for a large tribute
450 CE Marcian become eastern emperor and immediately halts payments to the Huns
451 CE Attila invades Gaul, where he is defeated by Aetius and the Goths, under Theodoric I, at Châlons
452 CE Attila invades Italy but spares Rome
453 CE Attila dies; Theodoric II becomes king of the Visigoths
454 CE The Hunnic Empire is overthrown by the subjected barbarians at the Battle of Netad; Valentinian III murders Aetius
455 CE Murder of Valentinian II; Geiseric invades Italy and sacks Rome
456 CE The Empire is dominated by the masters of the soldiers, Aspar the Alan (east) and Ricimer the Sueve (west)
457 CE Ricimer deposes Avitus and makes Majorian emperor, while Aspar makes Leo the eastern emperor
460 CE Destruction of Majorian’s fleet off Cartagena
461 CE Majorian deposed; Libius Severus becomes emperor.
465 CE Libius Severus dies; Ricimer rules as patrician; Asper falls from power in the east
466 CE Euric, king of the Visigoths, conquers Spain
467 CE Leo appoints Anthemius western emperor
468 CE Leo’s great expedition under Basiliscus, sent to crush Geiseric, is destroyed
472 CE Ricimer deposes Anthemius and set up Olybrius; death of Ricimer and Olybrius
473 CE Glycerius becomes western emperor
474 CE Julius Nepos becomes western emperor; Leo dies and is eventually succeeded in the east by Zeno the Isaurian
475 CE Romulus Augustus becomes the last western emperor
476 CE Odoacer deposes Romulus Augustus and ends the Roman Augustus of Constantinople; end of the Western Empire.