Note 62 — Chapter VI
E. J. (Edward James) Chinnock translation
The heavy cavalry, wholly or chiefly composed of Macedonians by birth, was known by the honourable name of ἑταίροι, Companions, or Brothers in Arms. It was divided, as it seems, into 15 ἴλαι, which were named after the States or districts from which they came. Their strength varied from 150 to 250 men. A separate one, the 16th Ilē formed the so-called agema, or royal horse-guard, at the head of which Alexander himself generally charged. See Arrian, iii. 11, 13, 18.