(Δεκέβαλος), was probably a title of honour among the Dacians equivalent to chief or king, since we find that it was borne by more than one of their rulers (Trebell. Poll. Trig. Tyrann. 100.10), and that the individual best known to history as the Decebalus of Dio Cassius is named Diurpaneus by Orosius, and Dorphancus by Jornandes.

This personage was for a long series of years, under Domitian and Trajan, one of the most enterprising and formidable among the enemies of Rome. Having displayed great courage in the field and extraordinary ability in every department of the military art, he was raised to the throne by the reigning sovereign, Douras, who abdicated in his favour. The new monarch quickly crossed the Danube, attacked and drove in the Roman outposts, defeated and slew Appius Sabinus, governor of Moesia, and, spreading devastation far and wide throughout the province, gained possession of many important towns and fortresses. Upon receiving intelligence of theæ calamities, Domitian hastened (A. D. 86) with all the troops he could collect to Illyria, and, rejecting the pacific though insulting overtures of Decebalus, committed the chef command to Cornelius Fuscus at that time prefect of the praetorium, an officer whose knowledge of war was derived from studies prosecuted within the halls of a marble palace amid the luxuries of a licentious court. The imperial general having passed the frontier on a bridge of boats at the head of a numerous army, perished after a most disastrous campaign, and the legions were compelled to retreat with the loss of many prisoners, an eagle, and the whole of their baggage and artillery. B'his failure again called forth Domitian from the city, but although he repaired to Moesia for the ostensible purpose of assuming the direction of affairs, he carefully abstained from exposing his person to the dangers of a military life, and moving from town to town, abandoned himself to his foul appetites, while his officers sustained fresh dishonour and defeat. Occasional glimpses of success, however, appear from time to time to have checked the victorious career of the barbarians, and especial mention is made of the exploits of a certain Julianus, who, in an engagement near Tapae, destroyed great numbers of the foe, and threatened even the royal residence, while Vezinas, who held the second place in the Dacian kingdom, escaped with difficulty bv casting himself among the slain, and feigning death until the danger was past. At length Domitian, harassed by an unprofitable and protracted struggle, and alarmed by the losses sustained in his contest with the Quadi and Marcomanni, was constrained to solicit a peace which he had more than once refused to grant. Decebalus despatched his brother, Diegis or Degis by name, to conclude a treaty, by whom some prisoners and captured arms were restored, and a regal diadem received in return. But the most important and disgraceful portion of the compact was for a time carefully concealed. Notwithstanding his pompous pretensions to victory and the mockery of a triumph, the emperor had been compelled to purchase the forbearance of his antagonist by a heavy ransom, had engaged to furnish him with a large body of artificers skilled in fabricating all instruments for the arts of peace or war, and, worst of all, had submitted to an unheard of degradation by consenting to pay an annual tribute. These occurrences are believed to have happened between the years A. D. 86-90, but both the order and the details of the different events are presented in a most confused and perplexing form by ancient authorities.

Trajan soon after his accession determined to wipe out the stain contracted by his predecessor, and at once refused to fulfil the conditions of the league. Quitting the city in his fourth consulship (A. D. 101), he led an army in person against the Dacians, whom he defeated near Tapae, the scene of their former misfortune, after an obstinate struggle, in which both parties suffered severely. Pressing onwards, a second victory was gained by Lusius Quietus, commander of the Moorish cavalry, many strongholds were stormed, the spoils and trophies taken from Fuscus were recovered, and the capital, Sarmazegetusa (Ζερμιζεγεθούσα), was invested. Decebalus having in vain attempted to temporize, was at length compelled to repair to the presence of the prince, and to submit to the terms imposed by the conqueror, who demanded not only the restitution of all plunder, but the cession of a large extent of territory. Trajan then returned to Rome, celebrated a triumph, and assumed the title of Dacicus. The war having been, however, soon renewed (A. D. 104), he resolved upon the permanent occupation of the regions beyond the Danube, threw a bridge of stone across the river about six miles below the rapid, now known as the Iron Gates, and being thus enabled to maintain his communications with ease and certainty, succeeded, after encountering a desperate resistance, in subjugating the whole district, and reducing it to the form of a province. (A. D. 105.) Decebalus, having seen his palace captured and his country enslaved, perished by his own hands, that he might not fall alive into those of the invaders. His head was sent to Rome, and his treasures, which had been ingeniously concealed beneath the bed of the river Sargetia, (now the Isfrig, a tributary of the Marosch,) which flowed beneath the walls of his mansion, were discovered and added to the spoil.

(D. C. 67.6, and note of Reimarus, 7, 10, 68.6-15; Tacit. Agric. 41; Juven. iv. and Schol.; Martial. 5.3, 6.76; Plin. Ep. 8.4, 9, 10.16; Sueton. Domit. 6; Eutrop. 7.15; Euseb. Chron. ; Zonar. 11.21; Oros. 7.10; Jornand. R. G. 13, Petr. Patric. Excerp. lep. p. 23, ed. 1648; Engel, Comment. de Trajan. eaped. ad Danub. Vindobon. 1794, p. 136; Mannert, Res. Traj. Imp. ad Danub. gest., 1793; Franke, Geschichte Trajans, 1837.