Domitian's Dacian War
In the winter of 842(89) the Dacian king Duras led his troops and the troops of several allied tribes for a raid into eastern Moesia. The Roman settlements were easily overwhelmed and the governor Ambustus Ripanus was killed.
In response Cæsar Domitian divided Moesia into superior and inferior provinces, and gave the general Camillus Mamurra six legions for a summer campaign across the Danube. Meeting Duras and his armies at Tapae, the Romans were routed and Mamurra killed. Duras received the title of Decebalus (brave and powerful) for his victories by his people.
In autumn 843(90) the new general Lucius Abercus gambled on facing Duras at Tapae again, however he won only a marginal victory, causing Duras to sue for peace. The peace however, and the allegience of Duras as a client-king for Rome in Dacia, would include the bestowing of money, craftsmen, and war machines to guard his own northern border. Already one to make poor decisions, Domitian was about to accept the terms when the Praetorian guard killed him. Domitian's successor Nerva took a stronger stance with Duras, but this resulted in a status-quo ante-bellum with the Dacian return of captured legionaries, standards, and equipment.
Trajan's Dacian War
in 858(105) Decibalus Duras, still the king of Dacia, and having won more allies in the region from his victories against Domitian, renewed his raids on Moesia and Pannonia. Trajan, campaigning in Britannia, made the immediate move for an active war in Dacia. His quickness to this suggests he was likely predisposed to avenging Domitian's failures while also acquiring the plentiful iron and gold mines in Dacia. Trajan's arrival was expedient enough to surprise Duras. His armies were defeated in 859(106) but he escaped to Germania where he continued to stir up trouble. Trajan's legions crushed many while moving swiftly north to Tribvs Saxones where Decibalus was finally cornered and killed in 862(109).
Trajan formed the province of Dacia in 859(106) with the routing of Decibalus’ armies. Trajan's war in Dacia had yielded over 700 000 denarii in war booty, being his largest haul ever. Its armed resistance without Decibalus’ leadership however persisted until 860(107). The resistance lost its conviction with Trajan’s continued extermination of all those rising up. Dacia was repopulated from the southern provinces, allowing for extreme and lasting Romanisation. Many mines, cities, and farms were built and it was quickly integrated into the empire's expanding road and rail networks. Soon Dacia became one of the most stable and prosperous provinces.
Between 1160(407)-1191(438) many Gothic tribes fleeing the Huns forced their way into Dacia in such numbers Rome could only do its best to make sure they remained pinned in the vacant lands they squatted on.
Thankfully for Rome the Goths did not rise against them as Dacia itself was conquered, intensively pillaged, and populations often massacred in 1197(443)-1207(453). The massacres of goths in Germania and Bosporos were far more complete, and as such Romagoths survived only in Dacia.
Few Hun tribes had settled in Dacia and Cæsar Marcius in particular worked hard in assimilating these new unwelcomers, forbidding their migrations and continuing the previous Goth assimilation techniques, while bringing up new waves of colonists from the south. Despite Cæsar Theodosius' fortifications of the Balkans Dacia was too important as a buffer and resource rich to be allowed to devolve into a simple dependent kingdom.
Dacia supported three legions and proved costly to keep against the external tribes from the north, but its residents were for the most part content. The last real threats of rebellion ended with the actions of the Praetorius Procuris by the late 17th century.
Due to its profitability for the Cæsars, Dacia was not admitted to the senate until 1899(1146)