The table counted the years starting from the presumed birth of Christ, rather than the accession of the emperor Diocletian on 20 November 284, or as stated by Dionysius: " sed magis elegimus ab incarnatione Domini nostri Jesu Christi annorum tempora praenotare ..." It is assumed Dionysius Exiguus intended either 1 AD or 1 BC to be the year of Christ's birth ( a " year zero " does not exist in this calendar ).

Ar., lxiv, and De Syn., xviii ), St Athanasius does not recall from memory being a first hand witness to the onset of the great persecution by the Tetrarchy of Diocletian and Maximian in February 303, for in referring to the events of this period he makes no direct appeal to his own personal recollections, but falls back on tradition.

Art dating from the Diocletian period ( 286 – 305 AD ) in Villa Romana del Casale, Sicily depicts women in garments resembling bikinis in mosaics on the floor.

Dalmatia was the birthplace of the Roman Emperor Diocletian, who, upon retirement from Emperor in AD 305, built a large palace near Salona, out of which the city of Split later developed.

After the Western Roman Empire collapsed in 476, with the beginning of the Migration Period, Julius Nepos shortly ruled his diminished domain from the Diocletian palace after his 476 flight from Italy.

Diocletian (; c. 22 December 244 – 3 December 311 ), was a Roman Emperor from 284 to 305.

Diocletian dated his reign from his elevation by the army, not the date of his ratification by the Senate, following the practice established by Carus, who had declared the Senate's ratification a useless formality.

There may have been a revolt in the eastern provinces at this time, because Diocletian brought settlers from Asia to populate emptied farmlands in Thrace.

The following spring, as Maximian prepared a fleet for an expedition against Carausius, Diocletian returned from the East to meet Maximian.

Diocletian invaded Germania through Raetia while Maximian progressed from Mainz.

Some time after his return, and before 293, Diocletian transferred command of the war against Carausius from Maximian to Flavius Constantius.

Diocletian spent the spring of 293 traveling with Galerius from Sirmium ( Sremska Mitrovica, Serbia ) to Byzantium ( Istanbul, Turkey ).

Diocletian left Africa quickly after the treaty, moving from Upper Egypt in September 298 to Syria in February 299.

Diocletian argued that forbidding Christians from the bureaucracy and military would be sufficient to appease the gods, but Galerius pushed for extermination.

On 1 May 305, Diocletian called an assembly of his generals, traditional companion troops, and representatives from distant legions.

Their homes were distant from political life, but Diocletian and Maximian were close enough to remain in regular contact with each other.

The historian Warren Treadgold estimates that under Diocletian the number of men in the civil service doubled from 15, 000 to 30, 000.

To avoid the possibility of local usurpations, to facilitate a more efficient collection of taxes and supplies, and to ease the enforcement of the law, Diocletian doubled the number of provinces from fifty to almost one hundred.

These dukes sometimes administered two or three of the new provinces created by Diocletian, and had forces ranging from two thousand to more than twenty thousand men.

Under the governance of the jurists Gregorius, Aurelius Arcadius Charisius, and Hermogenianus, the imperial government began issuing official books of precedent, collecting and listing all the rescripts that had been issued from the reign of Hadrian ( r. 117 – 38 ) to the reign of Diocletian.

In the edict, Diocletian declared that the current pricing crisis resulted from the unchecked greed of merchants, and had resulted in turmoil for the mass of common citizens.

* Diocletian from the Catholic Encyclopedia.

Eusebius references to the encampment of the Legio X Fretensis at Aila ( in southern Israel, near modern Aqaba and Eilat ); the X Fretensis was probably transferred from Jerusalem to Aila under Diocletian.

A further massive transfer of Bastarnae was carried out by emperor Diocletian ( ruled 284-305 ) after he and his colleague Galerius defeated a coalition of Bastarnae and Carpi in 299.

The title was also claimed by Carus ' other surviving son, Carinus, but Diocletian defeated him in the Battle of the Margus.

Similarly, Constantius defeated the British usurper Allectus, Maximian pacified the Gauls, and Diocletian crushed the revolt of Domitianus in Egypt.

It has been conjectured that he switched allegiances to support the claims of the future emperor Diocletian just before Diocletian defeated Carinus, the son of Carus, at the Battle of the Margus in July 285.

Both these views had some truth to them, despite the biases of their authors: Diocletian and the Tetrarchs did greatly expand the army, and the growth was mostly in frontier regions, although it is difficult to establish the precise details of these shifts given the weakness of the sources.

* Emperor Diocletian dispatched his son-in-law Galerius with a large army to Armenia.

Caesar Galerius led the pagan movement against Christianity and arrived to bring up Diocletian against Christianity in the year 302: first Christian soldiers had to leave the army, later the Church's property was confiscated and Christian books were destroyed.

Maximian joined the army, serving with Diocletian under the emperors Aurelian ( r. 270 – 275 ) and Probus ( r. 276 – 282 ).

On his way through Pannonia he put down the usurper Sabinus Iulianus, and encountered the army of Diocletian in Moesia.

In another account, the battle is represented as having resulted in a complete victory for Diocletian, for Carinus ' army deserted him.

The Roman Emperor Diocletian dispatched his son-in-law Galerius with a large army to Tiridates's aid.

By the time of Diocletian, emperors were openly " monarchs ", but the contrast with " kings " was maintained: Although the imperial succession was, de facto, generally hereditary, it was only hereditary if there was a suitable candidate acceptable to the army and the bureaucracy so the principle of automatic inheritance was not adopted.

In this phase, crystallised by the reforms of the emperor Diocletian ( ruled 284 – 305 ), the Roman army returned to regular annual conscription of citizens, while admitting large numbers of non-citizen barbarian volunteers.

The Late Roman army is the term used to denote the military forces of the Roman Empire from the accession of Emperor Diocletian in 284 until the Empire's definitive division into Eastern and Western halves in 395.

With the benefit of archaeological discoveries of recent decades, many contemporary historians view the late army as no larger than its predecessor: under Diocletian c. 390, 000 ( the same as under Hadrian almost 2 centuries earlier ) and under Constantine no greater, and probably somewhat smaller, than the Principate peak of c. 440, 000.

During the Diocletian Persecution of Christians, a commander of the Roman army, Saint Florian died as a martyr at Lauriacum on May 4, 304, when he was drowned in the Enns river.

In the late third or early 4th century ( probably during the reign of Diocletian ) the Roman army constructed an army camp measuring 100 x 100 m. on the northern side of the plateau.

In the first fifteen years of his rule, Diocletian purged the army of Christians, condemned Manicheans to death, and surrounded himself with public opponents of Christianity.

Christian tradition places the martyrdom of George, formerly a Roman army officer, in the reign of Diocletian.

Diocletian and Galerius also sent letters to the military command, demanding that the entire army perform the sacrifices or else face discharge.

Since it was Galerius's army that would have been purged — Diocletian had left his in Egypt to quell continuing unrest — Antiochenes would understandably have believed Galerius to be its instigator.