Ekdromoi Hoplitai are a special version of the Hoplite soldier, designed be fast enough to catch and kill skirmishers.
Ekdromoi Hoplitai are a specially equipped type of hoplites. They fight with little armor and no heavy equipment in order to be nimble enough to catch and kill skirmishers, especially Peltastai who became the bane of the heavily armored hoplites after they began to be used more extensively by Iphikrates. Their short spears carry a nasty punch for the lightly armed skirmishers and are able to outrange the better armored Peltastai. They carry the large hoplon shield in order to make up for this disparity, but they are not meant to engage in prolonged melee combat with standard hoplites. Their light leather armor is soft and layered with bronze plates and cloth in order to retard the missiles of the troops that they would likely be fighting. Their purpose is to serve as a professional light infantry that can neutralize the effect of missiles on the heavy infantry. The combination of light armor and speed makes this infantry a great counter to the ever pesky missile troops. They are not particularly useful against heavier infantry or even equivalent light infantry, due to their specialized nature.
These Hoplitai evolved in response to large scale use of Peltastai by Thebai and Athenai after the reforms of Iphikrates. Their armor evolved as well, over the years. They were originally armored with linen, but this was changed due to the fact that the linothorax was vulnerable to missile fire. The layered leather was developed after a period of trial and error, and functions much like modern tank armor does against projectiles. It intersperses hard and soft layers to dissipate the effect of missile weapons. This armor, while exceedingly useful against missiles, is only marginally effective against most melee weapons, due to its lightness and the concentrated force of the arm behind the melee weapon. Once the initial force of a missile weapon is dissipated it falls away harmlessly, but a melee weapon’s force doesn’t dissipate as radically as a missile weapon’s, since a missile weapon has a large amount of force propelling it, but that force is applied when the projectile is launched and it receives no more force after it is launched, while a melee weapon is given steady pressure that is much harder to dissipate.