The progress of the Roman arms, which, under the reign of Augustus, were carried to the banks of the Danube, brought them into contact with the Dacians, who were at that time governed by a warlike prince named Bærebestes, who boldly set the Roman conquerors at defiance. After his death, they were divided into four or five different principalities, and their strength was a good deal broken by the Romans; but their last king Decebalus, one of the ablest and most enterprising warriors of his time, re-united them into one body towards the 87th year of the Christian æra. The first irruption of the Dacians into the territory of the empire, took place during the latter part of Augustus’s reign; and, at times repulsed, at other times successful, they continued to annoy the Romans without any decisive advantage taking place on either side. At last the Emperor Domitian, determined to put a stop to their depredations, marched in person against them. The particulars of the war which ensued are sufficiently detailed in the Roman history. The result of it having been such as to compel Domitian to sue for peace; he consented to pay to Decebalus an annual sum in the shape of a pension, but which, in fact, was nothing less than a tribute. It was regularly paid by the Romans until the year 102, when the Emperor Trajan declared his resolution to discontinue it; and the Dacians thereby considering themselves no longer bound to observe the treaty of peace, crossed the Danube, and laid waste the Roman territory. Upon these acts of hostility, Trajan put himself at the head of a numerous army, and marching against them, forced them to retire, passed the Danube in pursuit, engaged and defeated their successive forces, and finally compelled Decebalus to acknowledge himself his vassal. Trajan then returned to Rome, where he received the honour of a triumph, and the title of _Dacicus_. But not long after, Decebalus, eager to shake off the Roman yoke, invaded and plundered the territory of his neighbours the Iazygæ, who were also tributary to the empire, on their refusal to join him against the Romans. Trajan again took the field at the head of a vast army, determined to chastise and subdue the Dacians. He reached the banks of the Danube in Autumn, and he thought it prudent to wait there the return of the fine season, that he might carry on military operations with more facility and success. It was during this interval, that he caused his famous bridge to be built over the Danube, under the direction of the architect Apollodorus of Damascus; and its present remains are sufficiently visible to verify the ancient accounts of this stupendous work. When the water is very low, some of the piles stand two or three feet above it, and render that part of the river difficult of navigation; they are looked upon as rocks by the natives of each side.