The Recovery, 260–284

Gallienus and the Threefold Empire260–268

The recovery began in the worst year and with the worst-served reputation in Roman historiography. Gallienus, sole emperor after his father's capture, ruled eight years over an empire from which the Rhine armies had seceded under Postumus — the imperium Galliarum of Book VI reborn with senate, consuls, and coinage, holding Gaul, Britain, and Spain and, the point the hostile tradition suppresses, holding the Rhine frontier competently while it did so — and in which the East had passed to Odaenathus of Palmyra, the caravan-city's prince who avenged Valerian by driving Shapur back from the Euphrates and was rewarded with the extraordinary title corrector totius Orientis: a client left to govern Rome's eastern half because Rome could not. Between them Gallienus held Italy, Africa, the Danube, and Illyricum against Alamannic invasions (checked at Mediolanum in 260 and 268), a Gothic sea-storm that sacked Athens, Corinth, Sparta, and Argos, and a chain of usurpations he suppressed one by one; and while doing it he executed the volume's decisive military reform. Barred from senatorial command by the crisis's own logic, he completed the transfer of legionary command to equestrian praefecti — after Gallienus no senator commands a legion, the constitutional revolution of the Principate's military settlement finished by attrition — and, more consequentially, assembled at Mediolanum a central mobile field army built around massed cavalry: the equites corps of Dalmatian and Moorish horse, promoted, paid, and stationed centrally rather than distributed along the perimeter. This was the structural answer to the crisis's structural problem: a linear frontier cannot meet simultaneous attacks, but a linear frontier plus a mobile reserve can meet them in sequence. Every emperor for the next two centuries fought with the instrument Gallienus improvised, and his own officers — the Illyrian cavalry generals Claudius, Aurelian, and Probus — were its first products, and his assassins: he was killed at Mediolanum in 268 besieging the last usurper of his reign, by a conspiracy of the men who would spend the next sixteen years using his army to save the empire he was afterward blamed for losing. Claudius II earned his cognomen Gothicus on it at Naissus in 269, breaking the greatest of the Gothic invasions in a battle whose casualty-claim of fifty thousand the Editor prints as claim and whose strategic effect — the Balkans cleared for a generation — is not in doubt; he died of plague within two years, and the recovery passed to the volume's central figure.

Aurelian, Restitutor Orbis270–275

Aurelian's five years reversed the crisis in every dimension, and the chapter narrates them as the compendium's fastest campaign-sequence. He began by fighting for Italy: the Vandals thrown back across the Danube, and then the Iuthungi and Alamanni, who broke into the peninsula and beat him at Placentia — the war's crisis, the road to Rome open — before being destroyed at Fanum Fortunae and Ticinum in 271. That emergency produced the volume's greatest monument: the wall of Rome, nineteen kilometers of brick-faced concrete with three hundred and eighty-one towers and eighteen gates, begun in 271 and built in less than a decade, incorporating whatever stood in its path — an amphitheater, tombs, an aqueduct's arches, the Pyramid of Cestius — the capital of the world, unwalled since the kings, putting on armor because the army could no longer promise that no enemy would reach it. He then abandoned Dacia, evacuating the province Trajan's Column celebrates and resettling its Roman population south of the Danube in a new Dacia Aureliana: the volume's second surrender of conquered territory, executed for the reason the first was, that the line could not be held with the force available — and the Editor marks the strategic honesty as the recovery's precondition. Then the reunification. In 272 he marched east against Palmyra, where Odaenathus's widow Zenobia, regent for her son Vaballathus, had converted the corrector's mandate into an empire — Syria, Arabia, Asia Minor to Ankara, and in 270 Egypt, the grain-source — and defeated her generals at Immae near Antioch and at Emesa with the same tactic twice: a feigned cavalry withdrawal drawing Palmyra's magnificent armored clibanarii into pursuit and exhaustion, then the infantry, then the Palestinian club-men against the armored horse. Palmyra was besieged, taken, and, when it revolted the next year, destroyed; Zenobia was captured at the Euphrates and walked, in gold chains, in the triumph of 274. Between the two Palmyrene campaigns he turned west: the Gallic empire, its fourth ruler Tetricus commanding an army that no longer believed in it, met him at Châlons in 274 and dissolved — Tetricus, by the tradition, having negotiated his own defeat, and receiving a governorship in Italy for it. The empire was whole for the first time in fourteen years, and its restorer took the title the coinage proclaims — RESTITUTOR ORBIS — reformed the currency toward a stabilized silver-washed aurelianianus, put the mint's own rioting workers down at the cost, Dio's successors say, of thousands of lives in Rome, dedicated the temple of the Unconquered Sun as an imperial monotheism-in-waiting, and was murdered in Thrace in 275 by his own staff officers, tricked into it by a secretary who had forged a proscription-list to save himself. The Editor lets the manner of his death stand as the crisis's epitaph: the man who reassembled the Roman world was killed by a clerk's lie, and his soldiers, discovering it, killed the clerk and asked the Senate to choose the next emperor.

To Diocletian275–284

The last nine years completed the pattern and produced the successor. Tacitus, the elderly senator the armies accepted, campaigned against Gothic raiders in Asia Minor and died within a year. Probus (276–282), the best of Aurelian's remaining lieutenants, cleared Gaul of the Franks and Alamanni in a campaign the sources credit with four hundred thousand square miles recovered and sixteen tribes broken, restored the German and Danubian lines, settled defeated barbarians inside the empire as laeti farming under obligation to serve — the beginning of the practice that will define Book VIII's frontier — put down three usurpers, and was killed by his own soldiers at Sirmium in 282 for setting them to drain marshes. His praetorian prefect Carus reigned two years, drove into Persia in 283 in the last successful Roman eastern offensive for a generation, took Seleucia and Ctesiphon — and died in his tent beyond the Tigris, by lightning in the official version, which the Editor grades as the version the army's officers preferred; his sons Carinus and Numerian divided the empire, and when Numerian died on the road home from Persia in 284 — carried in a closed litter, his death discovered by the smell — the army at Nicomedia held an inquest, executed the praetorian prefect Aper as the murderer, and on 20 November 284 acclaimed the commander of the household cavalry, a Dalmatian of obscure birth named Diocles who would style himself Diocletianus. He defeated Carinus at the Margus in 285 and then did what none of the soldier-emperors had managed: he reorganized the state so that the crisis could not recur in the same form — the empire divided into administrative halves and then quarters under colleagues, the provinces subdivided and grouped into dioceses, civil and military commands separated, the army enlarged and restructured around frontier troops and mobile field forces, the currency and taxation rebuilt on the annona's foundations, and the emperorship itself removed from human reach into the sacral, purple-veiled majesty of a Dominate. That reorganization, and the world it made, belong to Book VIII. This volume ends at the acclamation.