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
Greek units of measurement Greek units of measurement A number of units of measurement were used in Greece to measure length, mass, area, and capacity. In Greece, the metric system has been used since 1836 and was made compulsory in 1922. One "piki" varied from 0.640 m to 0.670 m. 1 "pic" was equal to 1 piki. The "small piki" of Constantinople (also known as the "endeze") was equal to 0.648 m The "large piki" of Constantinople (also known as the "arsin") was equal to 0.669 m A masonry "piki" (also known as the "meimar zire") was equal to 0.750 m. Two types of