The Third Battle of Tapae (101) was the decisive battle of the first of Trajan's Dacian Wars, in which the Roman Emperor defeated the Dacian King Decebalus's army. Other setbacks in the campaign delayed its completion until 102. The battle is most likely the battle-scene depicted on Plate 22 of Trajan's column.
It followed the earlier battles at the same place during Domitian's Dacian War.
Trajan's Dacian Wars (101–102, 105–106) were two military campaigns fought between the Roman Empire and the Dacians under King Decebalus during the reign of Emperor Trajan. The conflicts stemmed from repeated Dacian incursions into the province of Moesia and from Rome's growing need for resources. Discontent with the treaty Domitian had concluded with Decebalus in 89 CE persisted, and Trajan, keen to assert himself as a soldier-emperor, took the opportunity to reassert Roman authority.
Trajan's First Dacian War began in 101 CE, when the emperor led a major offensive across the Danube using a pontoon bridge constructed by his engineer Apollodorus of Damascus, who also cut a road through the river cliffs. The Romans won a series of victories, including at Tapae and Adamclisi. Before Trajan could capture the Dacian capital, Sarmizegetusa, Decebalus sought peace. The treaty forced him to surrender territory and engineers provided by Domitian, return equipment, accept Roman garrisons, and refrain from crossing the Danube.