Laudator Temporis Acti

Homer, Iliad 2.362-363 (Nestor speaking; tr. Peter Green):

Order your troops by their clans and by brotherhoods, Agamemnōn:
Thus brotherhood will bring aid to brotherhood, clan to clan.

κρῖν' ἄνδρας κατὰ φῦλα κατὰ φρήτρας Ἀγάμεμνον,
ὡς φρήτρη φρήτρηφιν ἀρήγῃ, φῦλα δὲ φύλοις.

G.S. Kirk in his commentary ad loc. cites N.G.L. Hammond and A. Andrewes.

N.G.L. Hammond, A History of Greece to 322 B.C. (Oxford: Clarendon Press, 1959), p. 67):

The epic saga is concerned primarily with the members of the princely class. They were individualistic in outlook, and stood above many of the restraints which were normal in contemporary society. In the struggle for power they committed murder even within their own families, and many of them paid little heed to the claims of 'phratry' or 'tribe'. But the society in which they lived was certainly organized on a more conservative system. Nestor, the representative of an older generation, told Agamemnon to muster the host before Troy by phratry and tribe, 'that phratry may aid phratry and tribes tribes'. The commoners, rather than the princes, were loyal members of these 'brotherhoods' (phratries), which were based on kinship and formed together into tribes. Anyone who was not a member of a brotherhood (aphretor) was an outcast from society. He could not become a member of a tribe or attend an Assembly.

A. Andrewes, "Phratries in Homer," Hermes 89.2 (1961) 129-140 (at 138, footnote omitted):

Homer's own experience gave him no help in imagining the military structure of a centralised kingdom such as Agamemnon's, and the stock of formulae which he inherited contained no hint of what a Mycenean army had been like. In the poet's own world organisation by phratries was a commonplace, but in the poems it is a disturbing intrusion. Through the bulk of the Iliad the army is essentially formless: if Homer had had in his mind a distinct idea how it was organised, he could never have treated it in the manner he does, inventing schemes of organisation for a momentary effect and forgetting them as soon as made. But there is of course one principle of cohesion, the loyalty of ἑταῖροι to their leader, and this principle is ubiquitous.