The population of Mesopotamia under the Parthians has been enlarged enormously, chiefly by Arabs, Iranians, and Aramaeans.

With the exception of the Roman occupation under Trajan (CE 98-117) and Septimius Severus (CE 193-211), the Arsacids rule until a new force of native Iranian rulers, the Sassanids, conquers the region in 227.

The year 193 opens in Rome with the murder of Emperor Commodus on New Year's Eve, December 31, 192 and the proclamation on New Year's Day of the City Prefect Pertinax as Emperor.

Pertinax is assassinated on March 28, 193, by the Praetorian Guard.

Didius Julianus outmaneuvers Titus Flavius Sulpicianus (Pertinax's father-in-law and also the new City Prefect) later that day for the title of Emperor.

Flavius Sulpicianus offers to pay each soldier twenty thousand sestertii to buy their loyalty (eight times their annual salary; also the same amount offered by Marcus Aurelius to secure their favors in 161).

Didius Julianus, however, offers twenty-five thousand to each soldier to win the auction and is proclaimed Emperor by the Roman Senate on March 28.

Three other prominent Romans also challenge for the throne: Pescennius Niger in Syria, Clodius Albinus in Britain, and Septimius Severus in Pannonia.

Septimius Severus marches on Rome to oust Didius Julianus and has him decapitated on June 1, 193, then dismisses the Praetorian Guard and executes the soldiers who had killed Pertinax.

Consolidating his power, Septimius Severus battles Pescennius Niger at Cyzicus and Nicaea in 193 and in 194 decisively defeats him at Issus.

Clodius Albinus initially supports Septimius Severus, believing that he will succeed him.

When he realizes in 195 that Severus has other intentions, Albinus has himself declared Emperor.

Severus devotes the following year to suppressing Mesopotamia and other Parthian vassals who had backed Niger.

Northern Mesopotamia, including Osroene, had come again under Roman control in the expedition of Lucius Verus in 161–166, but had not been formally organized into provinces; instead, they had been left under local vassal rulers, although Roman garrisons have been maintained, notably at Nisibis.

This control is threatened in 195, during the civil war between Severus and Niger, when rebellions break out in the area, and Nisibis is besieged.

Severus quickly restores order and organizes Osroene as a full province.

Both the Roman and Eastern churches, before the elevation of Victor to the Roman episcopacy—he had succeeded Eleuterus in about 189—had tolerated a difference in dating the celebration of the Christian Passover/Easter between Rome and the bishops of Asia Minor.

The churches in Asia Minor celebrate it on the fourteenth of the Jewish month of Nisan, the day before Jewish Passover, regardless of what day of the week it falls on, as the Crucifixion had occurred on the Friday before Passover.

The Latins call them Quartodecimans.

Rome and the West celebrate Easter on the Sunday following the fourteenth of Nisan.

Victor is remembered for the great concern he displayed for order in the church by severing ties with bishops such as Polycrates of Ephesus who opposed his views on Easter.

Pope Victor attempted to cut off from the common unity Polycrates and others for taking this stance, but later reversed his decision after Irenaeus and others intercede.

Polycrates is best known for his letter addressed to Victor: it will be used as proof against the argument that the Churches in Asia Minor accepted the authority of the bishops at Rome.

It is unclear what happened to Polycrates after his letter.

Victor also breaks with Theodotus of Byzantium for his beliefs about Christ: Theodotus claims that Jesus was born of the Virgin Mary and the Holy Spirit as a mortal man, and though later "adopted" by God upon baptism (that is to say, he became the Christ), was not himself God until after his resurrection.

This doctrine, sometimes called "Dynamic Monarchianism" or "Adoptionism,” is declared heretical by Victor, and Theodotus is excommunicated.

Until Victor's time, Rome celebrated the Mass in Greek.

Pope Victor changes the language to Latin, which is used in his native North Africa.

According to Jerome, he was the first Christian author to write about theology in Latin.

Latin masses, however, will not become universal until the latter half of the fourth century.

Severus, trying to gain favor with the family of Marcus Aurelius, rehabilitates Commodus's memory and has the Senate deify him in 195.

Troops loyal to the slain imperial claimant Pescennius Niger continue to occupy Byzantium, a valuable port of the Roman Empire.

Following a protracted siege, Septimius Severus, now Roman emperor, virtually destroys the city in 196, but later rebuilds it; it will quickly regain its previous prosperity.

Increasing friction between Severus and his rival-turned-heir Clodius Albinus had culminated in the latter’s reiterating his imperial claim.

Albinus had crossed with his legions to Gaul in early 195 and settled with his army near Lugdunum, where he has had himself proclaimed Augustus and makes plans to counter Severus.

Under his control, the Lugdunum mint issues coins celebrating his "clemency", as well as one dedicated to the "Genius of Lugdunum."

He is joined by an army under Lucius Novius Rufus, the governor of Hispania Tarraconensis.

They successfully attack the German troops of Virius Lupus, Legatus of one of the German provinces, but were unable to deter them from supporting Severus.

Severus’s policy of an expanded and better-rewarded army is criticized by his contemporary Dio Cassius and Herodianus: in particular, they pointed out the increasing burden (in the form of taxes and services) the civilian population had to bear to maintain the new army.

In order to maintain his enlarged military he has debased the Roman currency drastically.

Upon his accession he had decreased the silver purity of the denarius from 81.5% to 78.5%, but the silver weight had actually increased, rising from 2.40 grams to 2.46 grams.

Nevertheless the following year he debased the denarius substantially because of rising military expenditures.

The silver purity decreased from 78.5% to 64.5%—the silver weight dropping from 2.46 grams to 1.98 grams.

In 196 he reduces the purity and silver weight of the denarius again, to 54% and 1.82 grams respectively.

Severus' currency debasement is the largest since the reign of Nero, compromising the long-term strength of the economy.

However, Severus mints a much higher volume of denarii than his predecessors, alleviating some of the negative effects of debasement.

Prelude to the Battle of Lugdunum (196–197 CE): The Clash Between Septimius Severus and Clodius Albinus

By late 196 CE, Emperor Septimius Severus marched his army from Italy and Germany to confront his rival, Clodius Albinus, who had declared himself emperor in the West. This confrontation was part of the Roman civil war following the death of Emperor Pertinax (193 CE) and the struggle between Severus, Albinus, and Pescennius Niger for control of the empire.

The Initial Engagement at Tinurtium (Tournus, 196 CE)

• The armies of Severus and Albinus clashed at Tinurtium (modern Tournus, France), approximately 60 kilometers (37 miles) north of Lugdunum (modern Lyon) along the Saône River.
• The battle was inconclusive, neither side securing a decisive victory.
• Albinus withdrew southward, retreating toward Lugdunum, where he prepared for a final confrontationagainst Severus.

The Strategic Importance of Lugdunum

• Lugdunum (Lyon) was a key Roman stronghold in Gaul, serving as an economic and military hub.
• Control of the city was vital for maintaining dominance over western provinces, including Gaul and Britain, which Albinus governed as imperial governor.

The Path to the Final Battle (197 CE)

• After retreating to Lugdunum, Albinus fortified his position, expecting a major siege or pitched battle.
• Severus pursued Albinus aggressively, intent on eliminating his last serious rival for the throne.
• The Battle of Lugdunum (February 197 CE) would become one of the largest battles between Roman armies, deciding the fate of the empire.

Outcome and Historical Significance

• The final battle at Lugdunum ended with a decisive victory for Severus, securing his position as sole ruler of the Roman Empire.
• Albinus was defeated and either killed in battle or executed afterward.
• Severus consolidated his rule, launching purges against Albinus' supporters, further strengthening the Severan dynasty.

The events at Tinurtium and Lugdunum were crucial moments in the civil war that shaped the future of the empire, marking the triumph of Severus and the rise of the Severan dynasty (193–235 CE).

Severus again attacks Clodius Albinus to the northwest of the city, defeating the latter’s army on the nineteenth of February 197 in the bloody and decisive Battle of Lugdunum.

Dio Cassius describes three hundred thousand men involved in the battle: although this is one of the largest battles involving Roman armies known, this number is assumed to be an exaggeration.

The actual size of Severus’s army may be closer to seventy-five thousand men, mostly composed of Illyrian, Moesian and Dacian legions.

Albinus commits suicide in a house near the Rhône; his head is sent to Rome as a warning to his supporters.

His defeated cohorts are dissolved and the victorious legions punish those in Lugdunum who had supported Albinus, by confiscation, banishment, or execution.

The city is plundered or at least severely damaged by the battle.

Legio I Minervia will remain camped in Lugdunum from 198 to 211.

Historical and archaeological evidence indicates that Lugdunum never fully recovers from the devastation of this battle.

Severus departs for Italy and the East to resume the war against Parthia.