Hetairoi

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The Companion cavalry was composed of the Hetairoi of the king, mainly upper class citizens who were able to acquire and maintain armour and horses. In the age of Philip II and Alexander they were organized into 8 territorial squadrons, termed ilai. Each ile numbered between 200 and 300 horsemen and was commanded by two men, because as Arrian claims, Alexander "did not want anyone, not even his intimate friend, to be the centre of attention". After receiving reinforcements in Susa, Alexander established two companies in each squadron. They were referred to by the name of the territory they were mustered in or by the name of its captain. The Royal Ile was commanded by Alexander himself and contained twice the number of soldiers the other units contained, c. 400. These cavalry squadrons would sometimes be combined together in groups of two, three or four to form a hipparchy, which was commanded by a hipparch, though the whole Companion force was generally commanded by Alexander.