I have often wondered at a contention I have heard off repeated that a person is not really capable of having more than 300 or 350 personal relationships, even on social media, meaning that they can match names and faces and recall details and mutual interests held by these people. From speaking to military men or the officer class it does seem that specific unit cohesion becomes more of a managerial function than an exercise in direct leadership above Company level. Also, famous last stands seem to occur among units of defenders who number less than 500, usually far less.
I would like to recall, from resent reading of the ancients, primarily Thucydides, as read in the light of the poetics, with the bounds of class and community and blood so important to these authors. In one case, Thucydides does note that the Thebans came to the aid of a distant community of islanders, “...due to a community of the blood.” Many of the wars, even the disastrous Sicilian expedition, were undertaken based on ethnic alliances between home nations and their colonies.
We are familiar with the Spartan practice of having 300 picked men to fight with the king and of the Thebans with their sacred band of 300 men. Interestingly, 300 Athenians alone fought their way clear from Nicius' column on the desperate retreat from Syracuse where thousands failed. Of course there was the insane battle between two companies of 300 between Argos and Sparta in the mid 500s B.C.
What I would like to point out, is that Athenians, Syracusians and Spartans all tried to go this better, by employing special Battalions of 600. In all cases, these battalions failed. There was further the case that Spartans employed freedmen in groups of 300 that were literally fighting to confirm their free status.
Before gong on to the nature of the larger social structures, I should note that there was a famous ship among the Athenian navy, whose crew were super-democrats, who had served as revolutionaries in class wars ignited in various small states. 'The Crew of the Perilous' is not numbered. But based on the numbers of men shipped during the various expeditions, it seems unlikely that they numbered more than 300.
'The 400' who staged the oligarchic coup in Athens in the 20th year of the war, were notoriously ineffective as a body. However, they gained their power by each employing 120 youths as bullies and assassins. 'The 5,000' shadow rulers of Athens which the men in 'the camp at Samos' wanted to trust, who numbered about that number, might be an indication that groups in the thousands are regarded as too large to effectively conduct conspiracies against the public good.
Now to an overview of human society as a cascade of division from the ancient Greek perspective.
Alien
-Barbarians, including Persians, Carthaginians, Thracians, Sicilians and Iberians, were known to hold different social norms and were thought morally inferior. But were used regularly as allies against fellow Hellenes.
Co-Cultural
-Hellenes, held to the tradition of Homer, and were of the opinion that Trojan survivors had settled in Africa, Sicily and Italy. These people of the same cultural heritage were more likely to kill each other than people of other cultures and races.
Race
Dorians, Ionians, Boetians, Aeolians, Aetolians, such broad racial groups employed mutually compatible institutions as mentioned broadly by Thucydides. Racially, Ionians were said to have “dash” and Dorians [Spear-people] possessed a plodding, traditionalist character. Thus the Ionians of Syracuse rivaled the Ionian Athenians, their enemies, in innovation at sea.
Blood
As separate from race, being a specific bloodline, the relationship between a mother community and a colony is regarded as an attachment strong enough alone for war.
Community
The city, or polis, our very root word for the idea of politics and of a polity, was the most consistent and powerful bond. This bond was not undermined by Blood, Race or Culture above, as these were shared. They were undermined by internal divisions listed below.
Tribe/Clan
these ancient, vestigial affiliations seemed to have helped rather than hindered the Community, being its earliest component parts. They only seem to have caused problems in terms of scaling up action, with each tribe feeling it its right to have it general command on a given day, so that a community of ten tribes will have ten rotating generals, or two kings, etc. Tribe and clan was not documented in the history as having a corrosive effect on the community, but being a net advantage.
Faction-Party
Politics, were the single greatest danger to the community. Near every single war featured a dissident internal faction coordinating with a politically like-minded outsiders to topple their own city government. Oligarchs, Monarchists, tyranny advocates and democrats at various times tore every community apart and laid it open to enemies. Murder among democratic and oligarchic factions in Hellas, as demonstrated by the poets, in which Nestor declares the lover of civil war the enemy of mankind and the watcher over the House Atrides keeps “an ox on” his “tongue” to avoid being murdered, demonstrates levels of internal murder among the political class as high or higher than black-on-black homicides in postmodern Chicago or Baltimore.
Mysteries
Sacred institutions and priesthoods seem to have had no ill effects on communities in and of themselves. However, the extra-communal nature of these institutions were sometimes used as causes for war and internal political discord. Overall, these sacred institutions seemed to protect the community the most from unscrupulous individuals and were easily manipulated by factional conspiracies. The case of the Herme' and Alcibiades, who was the most dastardly person of his age, is a case in point. Likewise, the various border sacrifices and religious prohibitions against action held by the Dorians, while frustrating allied operations, had the effect of reducing the numbers of times these communities committed their men to war.
Individuals
The dissident individual generally seems to be chiefly a danger to democratic and imperial states. Just as the faction is the chief enemy of the oligarchic community, the remarkable individual which accounts for so much success among democracies and empires at war is a greater danger as an exile to a democracy than he is to an oligarchy. It may be that the democrats murdered dissidents at such high rates because they knew that their system promoted innovators to the forefront and that casting out embittered exiles among enemies was like giving over a new military technology to the foe.