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 Delium made use of planned tactical warfare for one of the first times in recorded history. In the previous centuries, battles between Greek city states were relatively simple encounters between massed formations of hoplites, where cavalry played no important role and all depended on the unity and force of the massed ranks of the infantry, straining against the opponent. At Delium, Pagondas made use of deeper ranks, reserves, cavalry interventions, light-armed skirmishers (peltasts) and gradual changes in tactics during the battle. These novelties were to be later exploited in more famous Theban victories in the following century, led by Epaminondas in