Setting out for Asia in 334 B.C., Alexander the Great commanded about 47,000 men, in combined infantry and cavalry units, part Macedonian and part levied from the Hellenic League. (See Diodorus for the composition.) They faced the Persian army for the first time, at the Granicus River, in Asia Minor, in May of 334. (Plutarch says the month was Thargelion.) Alexander's second-in-command, Parmenio, commanded the infantry phalanx. The Persian army of about 24,000 was led by satraps: Alexander did not face the Persian king Darius III himself until Issus in the autumn of 333 B.C.
Macedonian forces attacked, drawing out the Persian forces on one side using a move described as a feint attack. Meanwhile, Alexander rode with the Companion Cavalry, on the other side, and broke the weakened line of Persians. In the ensuing melee when the two sides met, Alexander was stunned with an axe, by Rhoesaces. Black Clitus killed Spithridates, who came up from behind, before he could deliver Alexander's death blow. Alexander won the battle, took about 2000 prisoners, and executed thousands of Greek mercenaries. He "liberated" Greek cities of Asia Minor from Persian rule. No longer need they pay the Persians tribute; now they could support Alexander's army.