This emperor at once began preparations for putting an end to his humiliating relations with Decebalus and his people, and although there have been many conjectures concerning his motives and intentions, there can be little doubt that his object was eventually, if not immediately, to incorporate Dacia with his empire.  Already in the reign of some of his predecessors the construction of a military road along the right or south bank of the Danube had been proceeding, and the first operation of Trajan was to hasten the completion of this road for the passage of his troops.[84] With this object he is said to have reconnoitred in 98 and 99, and the road probably attained completion as far as the bank opposite Orsova, about A.D. 100, as the tablet at Gradina, to which reference has already been made, indicates.  It is impossible for us to estimate the difficulties which must have attended this undertaking.  Possessing as we do explosives and rock-borers with which to break a passage through mountains and to blast rocky embankments, we can hardly understand how a people, with such limited mechanical appliances as then existed, can have surmounted the obstacles that presented themselves to their progress.  In one place the way was a plank road resting on beams, which were driven into the perpendicular face of the solid rock a few feet above the water’s edge, whilst a little further on it is seen to wind along terraces cut artificially, high up on the hillsides.  Hundreds if not thousands of lives must have been sacrificed in the work, for it must be remembered that the Roman generals and artificers had not only to combat natural difficulties, and to overcome the same obstacles as those which our modern engineers have to face, but that they were harassed by the savage but skilled enemy from the heights above, or from the opposite bank of the river, which here and there narrows itself into defiles 150 or 200 yards wide.

As soon as the road was sufficiently advanced for the passage of his army, A.D. 101, Trajan commenced his first expedition into Dacia.  The constitution and number of his forces are not accurately known.[85] They varied, according to different accounts, from 60,000 to 80,000 Romans, with a considerable number of allies, Germans, Sarmatians, Mauritanian cavalry, &c., the last-named under Lucius Quietus; and these Trajan is said to have assembled at a place somewhere south of Viminacium, which subsequently served as the base of his operations.[86]

Pages upon pages have been devoted by ancient and modern historians to surmises concerning the routes taken by Trajan in his expedition and the localities where his encounters with the Dacians took place, but in every case the ascertained facts have been few in number.  The best history of the campaigns is delineated in the bas-reliefs on Trajan’s Column[87] at Rome, and many details have been collected from fragmentary writings of Dion Cassius and other old historians.