Constantine I, also known as Constantine the Great, was a Roman emperor from AD 306 to 337 and the first Roman emperor to convert to Christianity. He played a pivotal role in elevating the status of Christianity in Rome, decriminalizing Christian practice and ceasing Christian persecution in a period referred to as the Constantinian shift. This initiated the cessation of the established ancient Roman religion. Constantine is also the originator of the religiopolitical ideology known as Constantinianism, which epitomizes the unity of church and state, as opposed to separation of church and state. He founded the city of Constantinople and made it the capital of the Empire, which remained so for over a millennium.
Diocletian, nicknamed Jovius, was Roman emperor from 284 until his abdication in 305. He was born Diocles to a family of low status in the Roman province of Dalmatia. Diocles rose through the ranks of the military early in his career, eventually becoming a cavalry commander for the army of Emperor Carus. After the deaths of Carus and his son Numerian on a campaign in Persia, Diocles was proclaimed emperor by the troops, taking the name Diocletianus. The title was also claimed by Carus's surviving son, Carinus, but Diocletian defeated him in the Battle of the Margus.
The labarum was a vexillum that displayed the "Chi-Rho" symbol ☧, a christogram formed from the first two Greek letters of the word "Christ" – Chi (χ) and Rho (ρ). It was first used by the Roman emperor Constantine the Great.
The 310s decade ran from January 1, 310, to December 31, 319.
Year 312 (CCCXII) was a leap year starting on Tuesday of the Julian calendar. In the Roman Empire, it was known as the Year of the Consulship of Constantinus and Licinianus. The denomination 312 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 Battle of the Milvian Bridge took place between the Roman Emperors Constantine I and Maxentius on 28 October 312 AD. It takes its name from the Milvian Bridge, an important route over the Tiber. Constantine won the battle and started on the path that led him to end the Tetrarchy and become the sole ruler of the Roman Empire. Maxentius drowned in the Tiber during the battle; his body was later taken from the river and decapitated, and his head was paraded through the streets of Rome on the day following the battle before being taken to Africa.
Galerius Valerius Maximianus was Roman emperor from 305 to 311. During his reign he campaigned, aided by Diocletian, against the Sasanian Empire, sacking their capital 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.
The Diocletianic or Great Persecution was the last and most severe persecution of Christians in the Roman Empire. In 303, the emperors Diocletian, Maximian, Galerius, and Constantius issued a series of edicts rescinding Christians' legal rights and demanding that they comply with traditional religious practices. Later edicts targeted the clergy and demanded universal sacrifice, ordering all inhabitants to sacrifice to the gods. The persecution varied in intensity across the empire—weakest in Gaul and Britain, where only the first edict was applied, and strongest in the Eastern provinces. Persecutory laws were nullified by different emperors at different times, but Constantine and Licinius' Edict of Milan in 313 has traditionally marked the end of the persecution.
The Battle of Adrianople was fought in Thrace on July 3, 324, during a Roman civil war, the second to be waged between the two emperors Constantine I and Licinius. Licinius was soundly defeated and his army suffered heavy casualties. Constantine built up military momentum, winning further battles on land and sea, eventually leading to the final defeat of Licinius at Chrysopolis.
The Battle of Cibalae was fought in 316 between the two Roman emperors Constantine I and Licinius. The site of the battle, near the town of Cibalae in the Roman province of Pannonia Secunda, was approximately 350 kilometers within the territory of Licinius. Constantine won a resounding victory, despite being outnumbered.
The Battle of Verona was fought in 312 between the forces of the Roman emperors Constantine I and Maxentius. Maxentius' forces were defeated, and Ruricius Pompeianus, the most senior Maxentian commander, was killed in the fighting.
Ruricius Pompeianus was Praetorian prefect and Commander of cavalry and infantry under Maxentius, Western Roman Emperor. While guarding the Adige and Po Rivers with the ample and well-directed forces of the province of Venetia, Pompeianus was killed by Constantine I's troops during the desperately fought Battle of Verona (312).
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.
Equites cataphractarii, or simply cataphractarii, were the most heavily armoured type of Roman cavalry in the Imperial Roman army and Late Roman army. The term derives from a Greek word, κατάφρακτος kataphraktos, meaning "covered over" or "completely covered".
The Vision of Constantine is an equestrian sculpture by the Italian artist Gian Lorenzo Bernini, located in the Scala Regia by St. Peter's Basilica in Vatican City. Originally commissioned as a free standing work of art within St. Peter's itself, the sculpture was finally unveiled in 1670 as an integral part of the Scala Regia - Bernini's redesigned stairway between St. Peter's Basilica and the Vatican Palace. Unlike other large works by Bernini, art historians have suggested that this work was almost entirely undertaken by him - no other sculptors have been recorded as receiving payment. Bernini's overall fee was 7,000 Roman scudi.
The German and Sarmatian campaigns of Constantine were fought by the Roman Emperor Constantine I against the neighbouring Germanic peoples, including the Franks, Alemanni and Goths, as well as the Sarmatian Iazyges, along the whole Roman northern defensive system to protect the empire's borders, between 306 and 336.
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.
The siege of Segusio or siege of Susa was the first clash of the civil war between the Roman emperors Constantine the Great and Maxentius in the spring of 312. In that year, Maxentius had declared war on Constantine, claiming to intend to avenge the death of his father Maximian, who had committed suicide after being defeated by him. Constantine would respond with an invasion of northern Italy.
