Aurelian in the context of "3rd century"

Diocletian (/ˌdaɪ.əˈkliːʃən/ DY-ə-KLEE-shən; Latin: Gaius Aurelius Valerius Diocletianus; Ancient Greek: Διοκλητιανός, romanized: Diokletianós; 242/245 – 311/312), 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. As with other Illyrian soldiers of the period, Diocles rose through the ranks of the military early in his career, serving under Aurelian and Probus, and 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.

Diocletian's reign stabilized the empire and ended the Crisis of the Third Century. He initiated the process of the Roman Empire split and appointed fellow officer Maximian as Augustus, co-emperor, in 286. Diocletian reigned in the Eastern Empire, and Maximian reigned in the Western Empire. Diocletian delegated further on 1 March 293, appointing Galerius and Constantius as junior colleagues (each with the title Caesar), under himself and Maximian respectively. Under the Tetrarchy, or "rule of four", each tetrarch would rule over a quarter-division of the empire. Diocletian secured the empire's borders and purged it of all threats to his power. He defeated the Sarmatians and Carpi during several campaigns between 285 and 299, the Alamanni in 288, and usurpers in Egypt between 297 and 298. Galerius, aided by Diocletian, campaigned successfully against Persia, the empire's traditional enemy, and in 299, he sacked their capital, Ctesiphon. Diocletian led the subsequent negotiations and achieved a lasting and favorable peace.

The antoninianus or pre-reform radiate was a coin used during the Roman Empire thought to have been valued at 2 denarii. It was initially silver, but was slowly debased to bronze with a minimal silver content. The coin was introduced by Caracalla in early 215 AD. It was silver, similar to the denarius, except that it was slightly larger and featured the emperor wearing a radiate crown, indicating it was a double denomination. Antoniniani depicting women (usually the emperor's wife) featured the bust resting upon a crescent moon.

Even at its introduction, the silver content of the antoninianus was only equal to 1.5 denarii. This created inflation: people rapidly hoarded the denarii (Gresham's law), while both buyers and sellers recognized the new coin had a lower intrinsic value and elevated their prices to compensate. Silver bullion supplies began running short because the Roman Empire was no longer conquering new territory, the Iberian silver mines had been exhausted, and a series of soldier emperors and usurpers needed coin to pay their troops and buy their loyalty. Each new issue of the antoninianus thus had less silver in it than the last, and thus contributed to ever-increasing inflation.

The Battle of Naissus in 268 or 269 was the defeat of a Gothic coalition by the Roman Empire under Emperor Gallienus (or Emperor Claudius II Gothicus) and the future Emperor Aurelian near Naissus (Niš). The events around the invasion and the battle are an important part of the history of the Crisis of the Third Century.

The result was a great Roman victory which, combined with the effective pursuit of the invaders in the aftermath of the battle and the energetic efforts of the future Emperor Aurelian, largely removed the threat from Germanic tribes in the Balkan frontier for the following decades.

The Aurelian Walls (Italian: Mura aureliane) are a line of city walls built between 271 AD and 275 AD in Rome, Italy, during the reign of the Roman Emperor Aurelian. They superseded the earlier Servian Wall built during the 4th century BC.

The walls enclosed all the seven hills of Rome plus the Campus Martius and, on the right bank of the Tiber, the Trastevere district. The river banks within the city limits appear to have been left unfortified, although they were fortified along the Campus Martius. The size of the entire enclosed area is 1,400 hectares (3,500 acres). The wall cut through populated areas: in reality the city at the time embraced 2,400 hectares (5,900 acres). Pliny the Elder in the first century AD suggested that the densely populated areas, extrema tectorum ("the limits of the roofed areas") extended 2.8 kilometres (1.7 mi) from the Golden Milestone in the Forum (Natural History 3.67).

Marcus Aurelius Claudius Quintillus (died 270) was a short-lived Roman emperor. He took power after the death of his brother, Emperor Claudius Gothicus, in 270. After reigning for a few weeks Quintillus was overthrown by Aurelian, who had been proclaimed rival emperor by the legions he commanded. The ancient sources variously report him to have killed himself, to have fallen in battle against Aurelian, or to have been murdered by his own soldiers.

The Palmyrene Empire was a short-lived breakaway state from the Roman Empire resulting from the Crisis of the Third Century. Named after its capital city, Palmyra, it encompassed the Roman provinces of Syria Palaestina, Arabia Petraea, and Egypt, as well as large parts of Asia Minor.

The Palmyrene Empire was ruled by Queen Zenobia, officially as regent for her son Vaballathus, who inherited the throne in 267 at age ten. In 270, Zenobia rapidly conquered most of the Roman east, attempting to maintain relations with Rome as a legitimate power. In 271, she claimed the imperial title for both herself and her son, fighting a short war with the Roman emperor Aurelian, who conquered Palmyra and captured Zenobia. A year later the Palmyrenes rebelled, which led Aurelian to raze Palmyra.

Gallic Empire or Gallo-Roman Empire are names used in modern historiography for a breakaway Western European part of the Roman Empire that functioned de facto as a separate state from 260 to 274. It originated during the Crisis of the Third Century, when a series of Roman military leaders and aristocrats declared themselves emperors and took control of Gaul and adjacent provinces without attempting to conquer Italy or otherwise seize the central Roman administrative apparatus.

The Gallic Empire was established by Postumus in 260 in the wake of barbarian invasions and instability in Rome, and at its height it included the territories of Germania, Gaul, Britannia, and Hispania. After Postumus' assassination in 269 it lost much of its territory but continued under several emperors and usurpers. It was retaken by Roman Emperor Aurelian after the Battle of Châlons in 274.

The Via Nomentana was an ancient Roman road in Italy, leading North-East from Rome to Nomentum (modern Mentana), a distance of 23 km (14 mi). It originally bore the name "Via Ficulensis", from the old Latin village of Ficulea, about 13 km (8.1 mi) from Rome. It was subsequently extended to Nomentum, but never became an important high road, and merged in the Via Salaria a few kilometers beyond Nomentum. It is followed as far as Nomentum by the modern state road, but some traces of its pavement still exist.

The road started at the Porta Collina in the Servian Walls until the third century, when emperor Aurelian built the Porta Nomentana in his new set of walls.