Hetairenreiterei
Alexander made a cautious and slow advance, intending to base his strategy on the structure of the Persian force. He led a flank of his Companion cavalry on the right, while the Thessalian cavalry were dispatched to the left, as a counter to Nabarsanes' mounted unit. Aware of the importance of the foothills to his right, Alexander sent a band of light infantry, archers, and cavalry to displace the defence Darius had stationed there. The enterprise was successful – those Persians not killed were forced to seek refuge higher in the mountains.