Editing Diocletian (section)

====Invasion, counterinvasion====
[[File:Diocletian medallion.jpg|thumb|left|Medallion of Diocletian, AD&nbsp;294]]
In 294, [[Narseh]], a son of Shapur who had been passed over for the Sassanid succession, came to power in Persia.{{sfnm|1a1=Potter|1y=2005|1p=292|2a1=Williams|2y=1985|2p=69}} In early 294, Narseh sent Diocletian the customary package of gifts between the empires, and Diocletian responded with an exchange of ambassadors. Within Persia, Narseh was destroying every trace of his immediate predecessors from public monuments. He sought to identify himself with the warlike kings [[Ardashir I]] (r. 226–241) and [[Shapur I]] (r. 241–272), who had defeated and imprisoned Emperor [[Valerian (emperor)|Valerian]] (r. 253–260) following his failed invasion of the [[Sasanian Empire]].{{sfn|Williams|1985|pp=69–70}}

Narseh declared war on Rome in 295 or 296. He appears to have first invaded western Armenia, where he seized the lands delivered to Tiridates in the peace of 287.<ref>[[Ammianus Marcellinus]] 23.5.11</ref>{{sfnm|1a1=Barnes|1y=1981|1p=17|2a1=CAH|2p= 81|3a1=Potter|3y=2005|3p=292|4a1=Southern|4y=2001|4p=149}} He moved south into Roman Mesopotamia in 297, where he inflicted a severe defeat on Galerius in the region between Carrhae ([[Harran]], Turkey) and Callinicum ([[Raqqa]], Syria), suggested by the historian [[Fergus Millar]] to have been somewhere on the [[Balikh River]].{{sfnm|1a1=Eutropius|1loc=9.24–25|2a1=Barnes|2y=1981|2p=17|3a1=CAH|3p=81|4a1=Millar|4y=1993|4pp=177–178}}  Diocletian may or may not have been present at the battle,{{sfn|Potter|2005|p=652}} but he quickly divested himself of all responsibility. In a public ceremony at [[Antioch]], the official version of events was clear: Galerius was responsible for the defeat; Diocletian was not. Diocletian publicly humiliated Galerius, forcing him to walk for a mile at the head of the Imperial caravan, still clad in the purple robes of the Emperor.<ref>[[Eutropius (historian)|Eutropius]] 9.24–25; [[Theophanes Confessor]], [https://archive.org/details/ByzantineAndNearEasternHistoryAD284813/page/n55/mode/1up AM 5793].</ref>{{sfnm|1a1=Barnes|1y=1981|1p=17|2a1=CAH|2p=81|3a1=Potter|3y=2005|3pp=292–293}}{{refn|It is possible 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, and not an attempt to humiliate him.{{sfn|Rees|2004|p=14}}|group="Note"}}

[[File:Arch-of-Galerius-1.jpg|thumb|Detail of [[Galerius]] attacking [[Narseh]] on the [[Arch and Tomb of Galerius#Arch of Galerius|Arch of Galerius]] at [[Thessaloniki]], [[Greece]], the city where Galerius carried out most of his administrative actions{{sfn|Rees|2004|p=14}}{{sfn|Southern|2001|p=151}}]]
Galerius was reinforced, probably in the spring of 298, by a new contingent collected from the empire's Danubian holdings.{{sfnm|1a1=Barnes|1y=1981|1p=18|2a1=CAH|2p=81|3a1=Millar|3y=1993|3p=178}} Narseh did not advance from Armenia and Mesopotamia, leaving Galerius to lead the offensive in 298 with an attack on northern Mesopotamia via Armenia.{{sfnm|1a1=Millar|1y=1993|1p=178|2a1=Potter|2y=2005|2p=293}}{{refn|[[Faustus of Byzantium]]'s history refers to a battle that took place after Galerius set up base at [[Satala]] (Sadak, Turkey) in [[Armenia Minor]], when Narseh advanced from his base at Oskha to attack him.{{sfn|CAH|p=81}}|group="Note"}} It is unclear if Diocletian was present to assist the campaign; he might have returned to Egypt or Syria.{{refn|Lactantius criticizes Diocletian for his absence from the front,{{sfn|Lactantius|loc=9.6}} but Southern, dating Diocletian's African campaigns one year earlier than Barnes, places Diocletian on Galerius's southern flank.{{sfn|Southern|2001|pp=151, 335–336}}|group="Note"}} 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 Sassanid cavalry. In two battles, Galerius won major victories over Narseh. During the [[Battle of Satala (298)|second encounter]], Roman forces seized Narseh's camp, his treasury, his harem, and his wife.{{sfnm|1a1=Barnes|1y=1981|1p=18|2a1=Potter|2y=2005|2p=293}} Galerius continued down the Tigris, and took the Persian capital Ctesiphon before returning to Roman territory along the Euphrates.{{sfnm|1a1=Barnes|1y=1981|1p=18|2a1=Millar|2y=1993|2p=178}}