Hetairoi

Hetairoi

During the reign of Philip, the Companions (Hetairoi in Greek) numbered at about 600 and they practically formed the elite guard of the king; after all, they were given the title  "the King's Companions" (Basilikoi Hetairoi). The Macedonian companions had remarkably competent horses of both Thessalian and Macedonian origin at their disposal, which were huskier than those of the cavalry of South Greece. Moreover, the companions were well-armed and heavily amoured, since they had sufficient financial means to provide themselves with the best weaponry available.

However, there was an issue; owing to their social structure, the way the Macedonian army operated and their limited manpower, the companions were not very effective on the battlefield, or, to say the least, they surely were not the ultimate force of the Macedonian army.

Philip, alongside his other great reforms, upended the companions as well. His first efforts aimed to increase the companions' manpower, which he did accomplish by promoting capable Macedonian, Thessalian and South Greek horsemen to the highest social class while providing them with land, privileges and great rewards.Thus, Philip managed to increase the companions' numbers more than threefold during his lifetime, leaving Alexander with at least 2.000 companions, a sheer force of heavy cavalry. 

During the reign of Alexander, if the phalanx of the 

Sarisoforoi functioned as the “anvil”, then the squadrons of the companions -the 

elite cavalry which consisted mainly of noble Macedonians- functioned as the “hammer”.

The latter were armed with the xyston and the kopis. The Xyston was lance 3 to 4 

meters long, which boasted a strong spearhead and a secondary spear-tip (known 

as σαυρωτήρα, or butt-spike) on its back. Its great length gave the companions the 

advantage even when facing hoplites phalanges. The kopis was a blunt sword 

featuring a single-edged blade and could be considered relatively long (80 to 90 

cm) for a Greek sword.