A cavalry answering to this in some respects had been employed by the later Persian monarchs, and was in use also among the Armenians at this period; but the Parthian pike was apparently more formidable than the corresponding weapons of those nations, and the light spear carried at this time by the cavalry of a Roman army was no match for it.
The force entrusted to Surenas comprised troops of both these classes.

No estimate is given us of their number, but it was probably considerable.

At any rate it was sufficient to induce him to make a movement in advance--to cross the Sinjar range and the river Khabour, and take up his position in the country between that stream and the Belik--instead of merely seeking to cover the capital.

The presence of the traitor Abgarus in the camp of Crassus was now of the utmost importance to the Parthian commander.

Abgarus, fully trusted, and at the head of a body of light horse, admirably adapted for outpost service, was allowed, upon his own request, to scour the country in front of the advancing Romans, and had thus the means of communicating freely with the Parthian chief.