11th August 106: Roman Emperor Trajan declares Dacia (modern Romania) a Roman province

The incorporation of Dacia into the Roman Empire marked the culmination of the Dacian Wars, which were fought between the Roman Empire and the Dacian Kingdom. The first war began in 101 CE and ended the following year with a Roman victory.
However, a second war erupted in 105 CE when Roman legions, under Trajan’s command, launched a decisive campaign against the Dacian King Decebalus. After a series of battles and sieges, the Romans captured the Dacian capital, Sarmizegetusa Regia. King Decebalus committed suicide to avoid capture, and the Dacian resistance collapsed.
The conquest of Dacia was a strategic and economic victory for Rome. The province was rich in natural resources, particularly gold and silver, so provided a substantial contribution to Rome’s economy and finance for further military and civic projects. The annexation of Dacia also extended Rome's northeastern frontier, providing a buffer against potential invasions from tribes beyond the Danube River.
Following the conquest, Trajan implemented a systematic process of Romanisation in Dacia including settlement by Roman colonists who established new towns and cities. New infrastructure was built such as roads, bridges, and forts, integrating Dacia into the imperial network. Meanwhile the local population adopted Roman customs, language, and laws, blending with the Roman settlers to form a distinct provincial culture.
In Rome, the establishment of Dacia as a province was commemorated through the erection of Trajan’s Column. However, in 271 AD Emperor Aurelian ordered Roman troops and settlers to leave Dacia, effectively ending imperial control over the region.