Battle of Gaugamela main Persian infantry was poorly trained and equipped in comparison to Alexander's pezhetairoi and hoplites. The only respectable infantry Darius had were his 2,000 Greek hoplites and his personal bodyguard, the 10,000 Immortals. The Greek mercenaries fought in a phalanx, armed not with a heavy shield but with spears no longer than three metres, while the spears of the Immortals were two metres long. Among the other Persian troops, the most heavily armed were the Armenians, who were armed the Greek way and probably fought as a phalanx. The rest of Darius' contingents were much more lightly armed; the main
Battle of Gaugamela weapon of the Achaemenid army historically was the bow and arrow, and javelin. Alexander commanded Greek forces from his kingdom of Macedon and the Hellenic League, along with Greek mercenaries and levies from the Paeonian and Thracian tributary peoples. According to Arrian, the most reliable historian of Alexander (who is believed to be relying on the work of the eyewitness Ptolemy), his forces numbered 7,000 cavalry and 40,000 infantry. Most historians agree that the Macedonian army consisted of 31,000 heavy infantry, including mercenaries and hoplites from other allied Greek states in reserve, with an additional 9,000 light infantry consisting mainly