Europe 296: Battle of Calleva Atrebatum
With the establishment of the Tetrarchy, Constantius took command in Gaul and immediately moved against Carausius, who he expelled from the major Gallic port of Gesoriacum in the summer of 293. However, it would be another three years before Constantius was ready to launch a fleet to cross the Channel and land two armies on the British coast. Carausius’ successor Allectus moved against the invaders, but was defeated near Calleva Atrebatum (Silchester), bringing an end to almost ten years of rebel rule in Britain.
The Agri Decumates was lost to the Romans in c.262, regained by Aurelian and Probus in 275–8, and lost again sometime between 290 and 310. The losses here seem not so much due to any rise in power of the local Alemanni tribe, but Roman internal division. When rival Roman factions controlled Gaul and Raetia, as was the case in 262–274 and 306, the limes of the Agri Decumates were no longer defensible and had to be abandoned.
Capitals of the First Tetrarchy
Officially, Rome remained the capital of the Roman Empire throughout the Tetrarchy. In practice, the real capital was wherever Diocletian’s court—and to a lesser degree, that of the other tetrarchs—resided. This varied considerably in the East, where Diocletian was initially based at Sirmium, in the Balkans, then joined Galerius in Antioch, before finally swapping places with his Caesar altogether by taking command at Antioch and Nicomedia while Galerius took charge in the Balkans (at Thessalonica and then Serdica). In the West the situation was less fluid: except for providing some brief support on the Rhine and a few years spent in Spain and Africa, Maximian remained based at Mediolanum, in Italy; his Caesar, Constantius, was largely based at Augusta Treverorum, in Gaul.
? Mar 293–1 May 305 Diocletian’s provincial reform▲
During his reign, the Roman emperor Diocletian increased the financial efficiency of the provincial governors by dividing up the Roman provinces, until their number had risen from about 50 to over 100. Most of these new provinces seem to have been introduced in the late 290s, possibly at around the same time. However, the province of Insulae, consisting of Rhodes and the Aegean islands, was separated from Asia by August 294, and some others may also have been formed this early.
293 Narseh vs Bahram III▲
In 293 Bahram II of the Sasanian Empire of Persia died and was succeeded by his son Bahram III with the strong support of the aristocrat Wahnam and the governor of Meshan. Rejecting someone they considered to be a weak ruler, the nobles of Persia instead rallied behind Bahram’s sexagenarian granduncle Narseh, the son of Shapur I and viceroy of Armenia. Facing little opposition, Narseh marched south on Ctesiphon, where Wahnam was put to death and Bahram agreed to end his four-month reign by abdicating.
293?–294? Busiris–Coptos revolt▲
In the early 290s the Upper Egyptian cities of Busiris and Coptos revolted against Roman rule. Diocletian dispatched Galerius to deal with the situation. Galerius captured both cities and razed them to the ground in reprisal.
293 Siege of Gesoriacum▲
Soon after being appointed Caesar in 293, Constantius laid siege to Gesoriacum (Boulogne), then under the control of the British-based usurper Carausius. To prevent the port from being relieved by the rebel fleet, he blocked the harbor entrance by sinking boulders there. Gesoriacum eventually capitulated, probably that summer, ending Carausius’ power in northern Gaul.
293 Constantius’ Frisian Campaign▲
While Constantius Chlorus was besieging Gesoriacum, the Chamavi and Frisii—two tribes now closely aligned to the Franks—occupied Batavia, the lower Scheldt, and the estuary of the Rhine. Constantius defeated both of these invaders in the summer of 293 and resettled them as indentured farmers on Roman lands in Gaul. This is one of the last mentions of the Frisii in the historical record; soon after this floods and warfare would render the region largely uninhabitable until the arrival of Angle and Saxon immigrants—the ancestors of modern Frisians—in the sixth century.
In 293 Carausius’ treasurer Allectus, possibly in response to the fall of Gesoriacum, had his master put to death and proclaimed himself emperor. He would reign in Britain for another three years before being overthrown by Constantius.
294 Diocletian’s Third Sarmatian Campaign▲
In 294, having established forts across the Danube opposite Aquincum and Sirmium, Diocletian launched a third campaign against the Sarmatians. It is probable that he crossed the Danube and used these forts as bases from which to overrun much of the Sarmatians’ territory. Many died in the ensuing carnage.
296 Carpian Campaign of 296▲
In 296 Roman forces led by either Diocletian or Maximian crossed the Danube and heavily defeated the Carpi. It is possible that this was a preventative measure to keep the Carpi in line before the emperor involved moved either to the East (if Diocletian) or to Gaul (if Maximian).
Sep 296 Battle of Calleva Atrebatum▲
By 296 Constantius had assembled two fleets—at Gesoriacum and at the mouth of the Seine—for the invasion of Britain, then under the control of the usurper Allectus. The Seine force, under Asclepiodotus, landed first, near the Isle of Wight, successfully evading the rebel fleet in the fog. Allectus hastily marched to meet the invaders, but was defeated and killed near Calleva Atrebatum (Silchester). The other force, under Constantius, landed near Londinium shortly after, restoring central Roman authority in Britain.