Decimus Brutus, with the siege of Mutina raised, had cautiously thanked Octavian, now commander of the legions that had rescued him, from the other side of the river.

Octavian coldly indicated he had come to oppose Antony, not aid Caesar's murderers.

Decimus had then been given the command to wage war against Antony, but many of his soldiers desert to Octavian.

His position deteriorating by the day, Decimus flees Italy, abandoning his legions and attempting to reach Macedonia, where Brutus and Cassius have stationed themselves.

Executed en route by a Gallic chief loyal to Mark Antony, Decimus Brutus becomes the first of Caesar's assassins to be killed.

… Dalmatia, and …

Bato the Daesitiate unsuccessfully attempts to take Salona, and after he is defeated by Messallinus, he withdraws north to join forces with the other Bato (Bato II), the leader of the Breuci.

The two centers of resistance unite in autumn 6 CE, and the two Batos become war-leaders of an allied rebel army.

The rebels give battle to a second Roman force from Moesia led by Caecina Severus (the governor of Moesia).

Despite their defeat, they inflict heavy casualties at the Battle of Sirmium.

The rebels are now joined by a large number of other communities.

The Roman invasion of Boiohaemum (Latin for "the home of the Boii"; present Bohemia), planned by Tiberius, has already been launched from two directions when news comes in CE 6 that Pannonia and Illyricum have revolted, posing the gravest threat to Italy since Hannibal's invasion.

At risk is the strategic province of Illyricum, recently expanded to include the territory of the Pannonii, the indigenous communities inhabiting the region between the rivers Drava and Sava, who had been subjugated by Rome in 12-9 BCE.

Illyricum is on Italy's eastern flank, exposing the Roman heartland to the fear of a rebel invasion.

Augustus accordingly orders Tiberius to break off operations in Germany and move his main army to Illyricum.

Tiberius sends Marcus Valerius Messalla Messallinus (the governor of Dalmatia and Pannonia) ahead with troops.

Other natives are recruited to fight against the Marcomanni as the rebellion swiftly overtakes enormous areas of the western Balkans and the Danube region.

Panic over the Illyrian revolt breaks out in Rome and Augustus raises a second task force under Tiberius's nephew Germanicus.

To do this, he resorts to the compulsory purchase and emancipation of thousands of slaves in order to amass enough troops.

This is the first time such a measure has been taken since the aftermath of the Battle of Cannae two centuries earlier.

At one moment, in winter CE 6/7, ten legions are deployed and an equivalent number of auxilia (seventy cohors, ten ala and more than ten thousand veterans).

Many within the legions are Roman war veterans.

In addition, they are assisted by a large number of Thracian troops deployed by their King Rhoemetalces, a Roman amicus (ally), for a grand total of some one hundred thousand men.

The region known as Dalmatia, a narrow coastal strip on the eastern side of the Adriatic Sea lying west of the Dinaric Alps and bordered by Istria in the north and by Kotor Bay in the south, had been the northern part of the Illyrian kingdom between the fourth century BCE until the Illyrian Wars in the 220s BCE and 168 BCE when the Roman Republic established its protectorate south of the river Neretva.

The area north of the Neretva had been slowly incorporated into Roman possessions until the province of Illyricum was formally established around 32-27 BCE.

The region had then become part of Illyricum.

The Dalmatians between 6 and 9 CE, had raised the last in a series of revolts together with the Pannonians, but the Romans have finally crushed the revolt in CE 10 and split llyricum into two provinces, Pannonia and Dalmatia.

Emperor Diocletian completes the decade-long construction of his magnificent palace on the Dalmatian coast at Salona (present Split, or Spalato, in Croatia).

Both residence and fortress, the palace follows the rectangular plan of a Roman military camp, corner towers and turrets surmounting its massive walls, and broad colonnaded avenues intersecting the enclosure.

The aged Diocletian has been living in retirement in the neighborhood of Salonae, on the edge of the Adriatic, where he has had a magnificent palace built (the modern town of Split, in Yugoslavia, occupies the site of its ruins).

He has seen his Tetrarchic system fail, torn by the selfish ambitions of his successors.

He has heard of Maximian's third claim to the throne, his forced suicide, his damnatio memoriae.

In his own palace, statues and portraits of his former companion emperor are torn down and destroyed.

Deep in despair and illness, Diocletian may have committed suicide.

The death of the former emperor on December 3, 311, occurs almost unnoticed.

The Vandals had next plundered the coasts of Dalmatia and …

Julius Nepos, former emperor of the Western Roman Empire, plots military actions in Dalmatia against Odoacer, hoping to regain control of Italy himself.