Spartan Mora regiments at Battle of Plataea

[Paullus Scipio]

Paralus wrote:

The text clearly states that the “Spartans themselves and the nearest of the Perioeci” set out at once for Pylos. These are those not already abroad in Attica (who’ve just returned and are to follow later). There seems nothing doubtful about the presence of perioeci in this initial force. ...not disputed at all.The whole Lakedaemonian Army was eventually present - the phrase "drawn from all the lochoi" clearly indicates that the six Spartan 'Morai'/12 'Lochoi' were all present following their brief 15 day foray into Attica. That the 'Perioikoi' were also present in force is also undoubted ( Diodorus[XII.61.2] records the total number of troops eventually present as 12,000 - six 'Morai' of Spartans with all 35 age classes called up will have numbered 6,720 on paper, plus a roughly equal number of 'Perioikoi', though I suspect that some of the Spartan troops, perhaps the oldest and youngest age-classes, may have stayed in Sparta.

Having departed in a hurry they arrive and immediately make plans to invest Pylos by both land and sea (4.8.1.4). At the same time they plan to block the harbour entrances with ships (when they arrive) and, in the “meanwhile, fearing that the enemy might make use of the island to operate against them, carried over some heavy infantry thither, stationing others along the coast”. Having determined this course of action they then select “from all the lochoi” the companies to send to the Island. The selection is best understood as being one enomotia drawn by lot from each of the 12 Lochoi i.e. 12x35=420This, one should note, was before any attack had been mounted upon Pylos by the Spartans. It is, therefore, a reasonable assumption that perioeci were a part of those initial heavy infantry (420) that had been sent across or any others that were to follow.
Thucydides wrote:

Having decided on this plan, they sent the hoplites across to the island, choosing the men by lot from all the lochoi'. Various parties had been across, done their spell of duty, and been relieved: the last of these forces to cross, and the one that was caught there, numbered 420 hoplites, with helots to attend on them.

Thucydides then goes on to describe the attacks on Pylos by the Lakedaemonian Army, and the subsequent Athenian victory, leaving the 420 and their helots stranded on Sphacteria. Then there is a truce, while peace talks take place in Athens, but terms cannot be agreed and the armistice ends. The trapped Spartans are now besieged, but supplies are smuggled through. Only then do Demosthenes and Cleon attack the island. It is quite clear that the last force/garrison of 420 are not drawn from the "initial" force which invests Pylos, as I said ! D

The measures taken by Sparta to retrieve the surviving 120 “officer” class men indicates the fragility of homoioi numbers.Agreed - but assuming the others were also Spartans would give them even more cause to try to recover them

The number of helots is not recorded. It is certain that the detailed numbers (the 120 of the “officer class”) found its way to Thucydides after they had been imprisoned in Athens. Whilst he then knew the numbers of the survivors his numbers (or their breakdown) for the original force were simply a total (Thucydides not having the component numbers).
Actually, Thucydides says "about 120 of the prisoners were 'Homioi'" - which implies the Athenians could not tell exactly who was who among the prisoners and had to estimate, as does the jibe thrown at them that the "best and bravest" ( i.e. the 'Homioi') were among the dead - re-inforcing the idea that all were Spartans, and no 'perioikoi were present.

In summary then, the following factors point toward the final force on Sphacteria being 'all-Spartan' :
*The size of the final force, drawn from "all the lochoi" is 12 (lochoi) x 35 (men per enomotia)= 420
* The force is accompanied by Helots ( which are exclusive to Spartans)
* The Athenians seem not to be able to distinguish 'Homioi' from the rest of the prisoners