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
Siege of Akragas (406 BC) the citizens, but a large number of mercenaries from Italy and Greece as well. Sicels and other native Sicilians also served in the army as hoplites and also supplied peltasts, and a number of Campanians, probably equipped like Samnite or Etruscan warriors, were present as well. The Phalanx was the standard fighting formation of the army. The cavalry was recruited from wealthier citizens and hired mercenaries. In a siege situation, old men and women served as impromptu peltasts. Large Sicilian cities like Syracuse and Akragas field up to 10,000 – 20,000 citizens, augmented by mercenaries or freed slaves whenever needed.