Invasion, counterinvasion In 294,
Narseh, a son of
Shapur I, who had been passed over for the Sasanid succession, came into power in Persia. Narseh probably moved to eliminate
Bahram III, a young man installed by a noble named Vahunam in the wake of Bahram II's death in 293. In early 294, Narseh sent Diocletian the customary package of gifts, but within Persia, he was destroying every trace of his immediate predecessors, erasing their names from public monuments. He sought to identify himself with the warlike reigns of
Ardashir (r. 226–241) and
Shapur (r. 241–272), who had sacked Roman Antioch and captured Emperor
Valerian. The historian Ammianus Marcellinus, circa 320–395, is the only source detailing the initial invasion of Armenia. Southern (1999, 149) dates the invasion to 295; Barnes (1982, 17, 293) mentions an earlier, unsuccessful invasion by Narseh based on the fact that the title
Persici Maximi was given to all four emperors; Odahl (2004, 59) concurs with Barnes and suggests that Saracen princes in the Syrian desert collaborated with Narseh's invasion. Narseh then moved south into Roman Mesopotamia, where he inflicted
a severe defeat on Galerius, then commander of the eastern forces, in the region between Carrhae (
Harran, Turkey) and Callinicum (
Raqqa, Syria). Diocletian may or may not have been present at the battle, but presented himself soon afterwards at Antioch, issuing an official version of events which placed all the blame for the affair upon Galerius. In Antioch, Diocletian forced Galerius to walk a mile in advance of his imperial cart while still clad in the purple robes of an emperor.
David Stone Potter reads a symbolic message in the display: the loss at Carrhae was due not to the failings of the empire's soldiers, but to the failings of their commander, and Galerius's failures would not be accepted. Another scholar, Roger Rees, suggests that Galerius's position at the head of the caravan was merely the conventional organization of an imperial progression, designed to show a
Caesar's deference to his
Augustus. on the
Arch of Galerius at
Thessaloniki,
Greece, the city where Galerius carried out most of his administrative actions. Galerius's army was reinforced probably in the spring of 298 by new contingents collected from the empire's Danubian holdings. Narseh did not advance from Armenia and Mesopotamia leaving Galerius to lead the offensive in 298 with an attack on northern Mesopotamia via Armenia. Diocletian may or may not have been present to assist the campaign. Narseh retreated to Armenia to fight Galerius's force, putting himself at a disadvantage; the rugged Armenian terrain was favorable to Roman infantry, but not to Sasanid cavalry. Local aid gave Galerius the advantage of surprise over the Persian forces, and he defeated Narseh in two successive battles. During the second encounter, the
Battle of Satala in 298, Roman forces seized Narseh's camp, his treasury, his harem, and his wife. Narseh's wife would live out the remainder of the war in Daphne, a suburb of Antioch, serving as a constant reminder to the Persians of the Roman victory. Galerius advanced into
Media and
Adiabene, winning continuous victories, most prominently near
Theodosiopolis (Erzurum), and securing
Nisibis (Nusaybin) before 1 October 298. The historian Timothy Barnes argues that he moved down the
Tigris, taking
Ctesiphon. Barnes's main argument for this is that Eusebius's biography of Constantine mentions that the later emperor had seen the ruins of
Babylon according to this work. Patricia Southern also argues that he took Ctesiphon based on the uncertainty of the location where the seizure of Narseh's wife and harem took place. However, no source ever specifically claims that Ctesiphon was sacked and many other historians argue Diocletian prevented him from moving further into Sasanian territory.
Peace negotiations Narseh had previously sent an ambassador to Galerius to plead for the return of his wife and children, but Galerius had dismissed this ambassador, reminding him of how Shapur had treated Valerian. In any case, the Romans treated Narseh's captured family well, perhaps seeking to evoke comparisons to
Alexander and his beneficent conduct towards the family of
Darius III. Peace negotiations began in the spring of 299, with both Diocletian and Galerius presiding. Their
magister memoriae (secretary) Sicorius Probus was sent to Narseh to present terms. The conditions of the
Peace of Nisibis were heavy: Persia would give up territory to Rome, making the Tigris the boundary between the two empires. Further terms specified that Armenia was returned to Roman domination with the fort of Ziatha as its border;
Caucasian Iberia would pay allegiance to Rome under a Roman appointee; Nisibis, now under Roman rule, would become the sole conduit for trade between Persia and Rome; and Rome would exercise control over the five satrapies between the Tigris and Armenia:
Ingilene, Sophanene (
Sophene), Arzanene (
Aghdznik),
Corduene, and
Zabdicene (near modern
Hakkâri, Turkey). These regions included the passage of the Tigris through the
Anti-Taurus range; the
Bitlis pass, the quickest southerly route into Persian Armenia; and access to the
Tur Abdin plateau. With these territories, Rome would have an advance station north of Ctesiphon, and would be able to slow any future advance of Persian forces through the region. Under the terms of the peace, Tiridates would regain both his throne and the entirety of his ancestral claim, and Rome would secure a wide zone of cultural influence in the region. Because the empire was able to sustain such constant warfare on so many fronts, it has been taken as a sign of the essential efficacy of the Diocletianic system and the goodwill of the army towards the tetrarchic enterprise. ==Rule as Augustus==