Europe 302: Battle of Lingones
Between 299 and 305 the Roman Empire went largely unthreatened by war, perhaps a testament to the general success of Diocletian’s reforms. One exception was in around 302, when an Alemannic raiding force almost captured Constantius at Lingones, deep within Gaul. However, Constantius soon defeated the invaders and drove them back across the Rhine, stabilizing that frontier as well.
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.
299 Peace of Nisibis▲
In the spring of 299 Diocletian met Galerius at Nisibis, where they laid out peace terms to present to Shah Narseh of Persia. Their demands included the cession of lands east of the Tigris to Rome, the restoration of Armenia as a Roman client, and the establishment of the Roman city of Nisibis as the sole point of trade between the two empires. Narseh accepted all these terms and in return had his wife and the other hostages seized at the Battle of Satala returned to him. It would be another four decades before Persia would challenge the Roman Empire again.
299 End of the Bastarnae▲
In 299 Galerius moved from Mesopotamia to the Balkans, where he established himself by building a new palace at Thessalonica. His first confrontation was with the Carpi and Bastarnae, who he defeated and resettled within the Roman Empire. This is the last confirmed mention of the Bastarnae by ancient sources and from here on they fade into obscurity.
299–300? Galerius’ Marcomannic Campaign▲
In 299 the Roman Caesar Galerius defeated the Marcomanni. It is possible that the Sarmatians and other tribes were also involved in this little-known encounter as Diocletian and Galerius were both awarded the title Sarmaticus maximus in 299/300.
301 Conversion of Tiridates III▲
By the end of the third century, Zoroastrianism was the dominant religion in Armenia but Christianity had gained a strong foothold. In 301, according to legend, the Christian Gregory the Illuminator miraculously cured the Armenian king Tiridates III of a severe illness, convincing the king to both adopt Christianity himself and make Armenia the first officially Christian state. For the rest of his reign, until his death in 330, Tiridates would work determinedly, and often forcefully, to convert his subjects to the new faith, completing the rift between Armenia and Zoroastrian Persia.
301 Edict on Maximum Prices▲
During his reign (284–305), Diocletian attempted to resolve the Roman Empire’s economic woes by introducing a stricter, more extensive tax system (the Capitatio-Iugatio), reforming the currency, and restricting social and professional mobility. However, inflation was still a major issue and in late 301 he attempted to curb it by issuing the Edict of Maximum Prices, which listed the highest prices merchants were legally allowed to charge for over one thousand goods. This move was an economic disaster, met widespread resistance, and only encouraged traders to shift to the black market. As a result the edict’s penalties were applied unevenly at best and within a few years it was dropped altogether.
302–304 Danubian War of 302–4▲
In 302–4 Galerius scored a further victory over the Sarmatians and three victories over the Carpi. He was partly aided in this war by Diocletian, who traveled along the Danube to Rome to celebrate his vicennalia (20th year of reign) in November 303. Many of the Carpi, having lost their homelands to the advancing Tervingi Goths, surrendered to the two rulers and were either conscripted into the Roman army or resettled in Pannonia.
302? Battle of Lingones▲
Some time after November 301, Caesar Constantius Chlorus was traveling across Gaul with a small escort when he was surprised by a vast force of invading Alemanni. Constantius fled to the nearby city of Lingones (Langres), which had already closed its gates but lowered ropes to let him up the wall. Once inside, he rallied his army and, with the support of the garrisons of the surrounding towns, decisively defeated the invaders some six hours later, allegedly killing 60,000 of them.