quality:corruption
Second Dacian war

Decebalus had no intention of remaining subject to Rome, or giving up his lost territory. As soon as he was able to, he took revenge on those who had supported Rome. He annexed territory from the Jazyges and violated the peace treaty by re-arming and receiving refugees and deserters from Roman territory. He also restored his fortifications. This time, Decebalus did not wait for Trajan to strike. In 105 he authorised a direct attack on the newly occupied Roman territory, probably the fortress at Banat. The attack seems to have taken Trajan and the Senate by surprise. Trajan immediately travelled north to review fortifications.

Meanwhile, Decebalus continued to disrupt Roman positions with guerrilla attacks. He also developed a plan to assassinate Trajan by using Roman auxiliaries who had defected to the Dacians to infiltrate the emperor's camp. The plot failed. However he succeeded in capturing one of Trajan's senior officers, Pompeius Longinus, whom he tried to use as a hostage to bargain with Trajan. Longinus took poison to avoid being so used.

Trajan, meanwhile, was building a large force for a full-scale invasion. Decebalus tried to negotiate a peace settlement, but Trajan demanded that Decebalus surrender himself, which he refused to do. Decebalus' allies among the surrounding tribes seem to have deserted him at this point. Trajan launched a direct attack on the Dacian capital, Sarmizegetusa. After a long siege of Sarmizegetusa and a few skirmishes in the nearby region, the Romans conquered the Dacian capital. Decebalus managed to escape with his family. He and his remaining supporters continued a guerrilla campaign in the Carpathian mountains.