The Tetrarchy was the system instituted by Roman emperor Diocletian in 293 AD to govern the ancient Roman Empire by dividing it between two emperors, the augusti, and their junior colleagues and designated successors, the caesares.
The 300s decade ran from January 1, 300, to December 31, 309.
The 310s decade ran from January 1, 310, to December 31, 319.
Year 305 (CCCV) was a common year starting on Monday of the Julian calendar. At the time, it was known as the Year of the Consulship of Constantius and Valerius. The denomination 305 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
The 290s decade ran from January 1, 290, to December 31, 299.
The 280's decade ran from January 1, 280, to December 31, 289.
Year 303 (CCCIII) was a common year starting on Friday of the Julian calendar. It was known in the Roman Empire as the Year of the Consulship of Diocletian and Maximian. The denomination 303 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 308 (CCCVIII) was a leap year starting on Thursday of the Julian calendar. It was known in the Roman Empire as the Year of the Consulship of Diocletian and (Galerius) Maximianus. The denomination 308 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 307 (CCCVII) was a common year starting on Wednesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Severus and Maximinus. The denomination 307 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 310 (CCCX) was a common year starting on Sunday of the Julian calendar. At the time, it was known as the Year of the Consulship of Andronicus and Probus. The denomination 310 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Flavius Valerius Constantius, also called Constantius I, was a Roman emperor from 305 to 306. He was one of the four original members of the Tetrarchy established by Diocletian, first serving as caesar from 293 to 305 and then ruling as augustus until his death. Constantius was also father of Constantine the Great, the first Christian emperor of Rome. The nickname "Chlorus" was first popularized by Byzantine-era historians and not used during the emperor's lifetime.
Galerius Valerius Maximianus was Roman emperor from 305 to 311. While acting as Caesar under Emperor Diocletian, Galerius obtained victory warring against the Sassanian Empire, defeating Narseh at the battle of Satala in 298 and possibly sacking the Sassanian capital of Ctesiphon in 299. He also campaigned across the Danube against the Carpi, defeating them in 297 and 300. Although he was a staunch opponent of Christianity, Galerius ended the Diocletianic Persecution when he issued the Edict of Toleration in Serdica (Sofia) in 311.
Maximian, nicknamed Herculius, was Roman emperor from 286 to 305. He was Caesar from 285 to 286, then Augustus from 286 to 305. He shared the latter title with his co-emperor and superior, Diocletian, whose political brain complemented Maximian's military brawn. Maximian established his residence at Trier but spent most of his time on campaign. In late 285, he suppressed rebels in Gaul known as the Bagaudae. From 285 to 288, he fought against Germanic tribes along the Rhine frontier. Together with Diocletian, he launched a scorched earth campaign deep into Alamannic territory in 288, refortifying the frontier.
Marcus Aurelius Valerius Maxentius was a Roman emperor from 306 until his death in 312. Despite ruling in Italy and North Africa, and having the recognition of the Senate in Rome, he was not recognized as a legitimate emperor by his fellow emperors.
Flavius Valerius Severus, also called Severus II, was a Roman emperor from 306 to 307, and a member of the Tetrarchy. He shared control of the western half of the empire with Constantine I, but spent most of his short reign in a civil war against the usurper Maxentius, who later killed him and took over Italy.
In historiography, the Late or Later Roman Empire, traditionally covering the period from 284 CE to 641 CE, was a time of significant transformation in Roman governance, society, and religion. Diocletian's reforms, including the establishment of the tetrarchy, aimed to address the vastness of the empire and internal instability. The rise of Christianity, legalized by Constantine in 313 CE, profoundly changed the religious landscape, becoming a central force in Roman life. Simultaneously, barbarian invasions, particularly by the Goths and Huns, weakened the Western Roman Empire, which collapsed in 476 CE. In contrast, the Eastern Roman Empire endured, evolving into the Byzantine Empire and laying the foundations for medieval Europe.
Valeria Maximilla was a Roman Empress and wife of Emperor Maxentius.
The civil wars of the Tetrarchy were a series of conflicts between the co-emperors of the Roman Empire, starting from 306 AD with the usurpation of Maxentius and the defeat of Severus to the defeat of Licinius at the hands of Constantine I in 324 AD.
The Conference of Carnuntum was a gathering of ancient Roman rulers on 11 November 308, intended to stabilize the power-sharing arrangement known as the Tetrarchy. It was convened by the Eastern augustus (emperor) Galerius in the city of Carnuntum, which at the time was located in the Roman province of Pannonia Prima. A dispute over the title of augustus in the West had been ongoing since the previous year, when consecutive invasions by Severus II and Galerius had failed to recover Italy from the usurpers Maxentius and Maximian. Present at the conference were the retired Diocletian, and his former colleague, Maximian.
The Battle of Brescia was a confrontation that took place during the summer of 312, between the Roman emperors Constantine the Great and Maxentius in the town of Brescia, in northern Italy. Maxentius declared war on Constantine on the grounds that he wanted to avenge the death of his father Maximian, who had committed suicide after being defeated by him. Constantine would respond with a massive invasion of Italy.
