Quintus Curtius Rufus, History of Alexander 8.14.5

8.14.5

Contra Alexander expedito ac levi agmine strenue invectus est. Scythae et Dahae primi omnium invasere Indos: Perdiccam deinde cum equitibus in dextrum cornu hostium emisit.

He was already in full march at the head of his army, which he had divided into two columns, when the tidings reached Porus that the bank was occupied by a military force, and that the crisis of his fortunes was now imminent. In keeping with the infirmity of our nature, which makes us ever hope the best, he at first indulged the belief that this was his ally Abisares come to help him in the war as had been agreed upon. But soon after, when the sky had become clearer, and showed the ranks to be those of the enemy, he sent 100 chariots and 4000 horse to obstruct their advance. The command of this detachment he gave to his brother Hages. Its main strength lay in the chariots, each of which was drawn by four horses and carried six men, of whom two were shield-bearers, two, archers posted on each side of the chariot, and the other two, charioteers, as well as men-at-arms, for when the fighting was at close-quarters they dropped the reins and hurled dart after dart against the enemy. But on this particular day these chariots proved to be scarcely of any service, for the storm of rain, which, as already said, was of extraordinary violence, had made the ground slippery, and unfit for horses to ride over, while the chariots kept sticking in the muddy sloughs formed by the rain, and proved almost immovable from their great weight. Alexander, on the other hand, charged with the utmost vigour, because his troops were lightly armed and unencumbered.

The Scythians and Dahae first of all attacked the Indians, and then the king launched Perdiccas with his horse upon their right wing. The fighting had now become hot everywhere, when the drivers of the chariots rode at full speed into the midst of the battle, thinking they could thus most effectively succour their friends. It would be hard to say which side suffered most from this charge, for the Macedonian foot-soldiers, who were exposed to the first shock of the onset, were trampled down, while the charioteers were hurled from their seats, when the chariots in rushing into action jolted over broken and slippery ground. Some again of the horses took fright and precipitated the carriages not only into the sloughs and pools of water, but even into the river itself.