** Battle of Lingones — Caesar Constantius Chlorus defeats the Alemanni

Soon after his father's death Constantius is supposed to have ordered a massacre of his relatives descended from the second marriage of his paternal grandfather Constantius Chlorus, though the details are unclear.

In 293, Constantius Chlorus launched a second offensive, besieging the rebel's port at Boulogne and cutting it off from naval assistance.

Constantius Chlorus returned in 306, aiming to invade northern Britain.

His paternal grandparents were Western Roman Emperor Constantius Chlorus and his second wife, Flavia Maximiana Theodora.

Constantius II ordered the murders of many descendants from the second marriage of Constantius Chlorus and Theodora, leaving only Constantius and his brothers Constantine II and Constans I, and their cousins, Julian and Gallus ( Julian's half-brother ), as the surviving males related to Emperor Constantine.

* 293 – Roman Emperors Diocletian and Maximian appoint Constantius Chlorus as Caesar to Maximian.

* 250 – Constantius Chlorus, Roman Emperor ( d. 306 )

In 293, feeling more focus was needed on both civic and military problems, Diocletian, with Maximian's consent, expanded the imperial college by appointing two Caesars ( one responsible to each Augustus ) — Galerius and Constantius Chlorus.

* Augusta Treverorum ( modern Trier, in Germany ) was the capital of Constantius Chlorus, the western Caesar, near the strategic Rhine border, it had been the capital of Gallic emperor Tetricus I ; this quarter became the prefecture Galliae.

Their Caesares, Galerius and Constantius Chlorus, were both raised to the rank of Augustus, and two new Caesares were appointed: Maximinus ( Caesar to Galerius ) and Flavius Valerius Severus ( Caesar to Constantius ).

:: Gallia et Hispaniae Constantius Chlorus ( 293 – 305 )

:: Gallia, Hispaniae et Britannia Constantius Chlorus ( 305 – 306 )

The first book sketches briefly the history of the early Roman emperors from Augustus to Diocletian ( 305 ); the second, third and fourth deal more fully with the period from the accession of Constantius Chlorus and Galerius to the death of Theodosius I ; the fifth and sixth, the most useful for historians, cover the period between 395 and 410, when Priscus Attalus was deposed ; for this period, he is the most important surviving non-ecclesiastical source.

* Constantius Chlorus and Galerius are declared Augusti ; Flavius Valerius Severus and Maximinus II Daia are appointed Caesars.

Constantius Chlorus requests leave for his son Constantine I who remains at Galerius's court in Nicomedia, as a virtual hostage.

* Battle of Lingones: Constantius Chlorus defeats the Alamanni in the territory of the Lingones ( Langres ) in Gaul.

* Constantius Chlorus defeats the Alemanni and fortifies the town of Konstanz ( Germany ).

Medal of Constantius Chlorus capturing Roman London | Londinium ( 296 )

* Constantius Chlorus assembles two invasion fleets with the intent of crossing the English Channel.

He came from Antioch and served under Constantius II and was probably appointed to ensure that nobody with western associations was serving in Britain during a time of mistrust, rebellion and suppression symbolised by the brutal acts of the imperial notary Paulus Catena.

Constantius was assigned Gaul and Britain.

Constantius remained in Britain for the rest of the time he was part of the Tetrarchy, dying in York in July 306.

After the defeat and death of Magnentius in the Battle of Mons Seleucus in 353, Constantius II dispatched his chief imperial notary Paulus Catena to Britain to hunt down Magnentius ' supporters.

In the West, the Augustus Maximian controlled the provinces west of the Adriatic Sea and the Syrtis, and within that region his Caesar, Constantius, controlled Gaul and Britain.

* Constantius II sends his official Paulus Catena to Britain to hunt down the opponents of Magnentius.

Constantine, disappointed in his hopes to become a Caesar, fled the court of Galerius after Constantius had asked Galerius to release his son as Constantius was ill. Constantine joined his father's court at the coast of Gaul, just as he was preparing to campaign in Britain.

In 305 Constantius crossed over into Britain, travelled to the far north of the island and launched a military expedition against the Picts, claiming a victory against them and the title Britannicus Maximus II by 7 January 306.

According to Geoffrey of Monmouth's History of the Kings of Britain ( 1136 ), Constantius was sent to Britain by the Senate after Asclepiodotus, here a British king, was overthrown by Coel of Colchester.

Constantius married Coel's daughter Helena and became king of Britain.

The identification of Helena as British had previously been made by Henry of Huntingdon, but has no historical validity: Constantius had divorced Helena before he went to Britain.

Constantius himself, it seems, did not reach Britain until it was all over, and his panegyrist claims he was welcomed by the Britons as a liberator.

Constantius was a friend of Bishop Lupus of Troyes, who accompanied Germanus to Britain, which provided him with a link to Germanus.

Germanus may have made a second visit to Britain in the mid 430s or mid 440s, though this is contested by some scholars who suggest it may be a ' doublet ' or variant version of the visit that has been mistaken as describing a different visit and erroneously included as such by Constantius, according to whom Germanus was joined by Severus, Bishop of Trier and met Elafius, described by Bede as ' a chief of that region '.

In 296 the general Constantius Chlorus invaded Britain to reclaim Britain for Rome.

Rome, apparently, was pleased that Britain had a new king and sent a senator, Constantius Chlorus, to negotiate with Coel.

The system of the Tetrarchy quickly ran aground when the Western Roman Empire's Constantius died unexpectedly in 306, and his son Constantine the Great was proclaimed Augustus of the West by the legions in Britain.

In 296 he assisted the western Caesar Constantius Chlorus in re-establishing Roman rule in Britain following the illegal rules of Carausius and Allectus.

Allectus, having assassinated Carausius in 293, remained in control of Britain until 296, when Constantius staged an invasion to retake the island.

In 305, Constantius Chlorus re-invaded the northern lands of Britain although the sources are vague over their claims of penetration into the far north and a great victory over the " Caledones and others " ( Panegyrici Latini Vetares, VI ( VII ) vii 2 ).

Under Constantine the cities lost their revenue from local taxes, and under Constantius II ( r. 337 – 361 ) their endowments of property.

Most of the cities were not rebuilt, save Salamis which was rebuilt on a smaller scale and renamed Constantia after the Roman Emperor Constantius II, son of Constantine the Great, residing in Constantinople.