The Macedonians ' central phalanx crossed the river and clashed with the renegade Greek mercenaries who fronted Darius ' vanguard .
The Macedonian left wing , commanded by Parmenion , was meanwhile driven back by Nabarsanes ' large cavalry .
The Macedonian ' central phalanx crossed the river and clashed with the renegade Greek mercenaries who fronted Darius ' vanguard .
The Macedonian left wing , commanded by Parmenion , was meanwhile driven back by Nabarsanes ' large cavalry .