Upon the death of Alexander the Great, the Macedonian empire lacked a clear heir. Accordingly, his leading generals, the Diadochoi (the Successors), divided power amongst themselves as a temporary measure while they manoeuvred to overcome their rivals and secure sole power for themselves. Nobody succeeded in the task, and as a result the various fragments continued an independent existence until the end of the Hellenistic era. The leading contenders in the immediate struggle were all Macedonian aristocrats, save for Eumenes, Alexander's Greek military secretary. As a Greek, he could never hope to gain the throne vacated by Alexander himself, so he acted in the name of Alexander's posthumously-born infant son. Each Successor's initial force differed in composition, reflecting the troops they had either inherited from holding an independent command under Alexander (as was the case of Antipatros, Krateros or Antigonos) or had been doled out in the initial division of power (Perdikkas, Ptolemy or Seleukos for instance).
In such a climate, military resources were at a premium. Faced with a finite, and indeed, strictly limited number of Macedonian troops, the Successors had two courses open to them if they wanted to enlarge their armies. The most obvious one was to raise troops from amongst the non-Macedonian peoples subject to them. This was something of a two edged sword however, since an armed and trained native populace was that much more likely to rebel. Native uprisings had to be constantly guarded against. Antigonos made much use of Lykians and Paphlagonians, who had long been accustomed to Greeks and Greek warfare (they were fighting as Greek hoplites as least as long ago as Herodotos' day), but he was the exception that proved the rule. Ptolemy at the battle of Gaza made use of a small number native Egyptians, and he may have done so elsewhere, but this was probably not considered a success to judge from the alacrity his son introduced Jewish military settlers, and the later propensity of the Egyptians to revolt against the Macedonian occupiers. The Persians refused to serve any but Peukestas - which I would posit is why Peukestas survive the aftermath of Eumenes' defeat by Antigonos, while many of the Medes, who had contributed light cavalry to Antigonos' cause, thereafter gained independence forming the state commonly referred to as Media-Atropatene. The other, and more widely adopted alternative, was to fall back on mercenary troops. Alexander of course had used huge numbers of mercenaries himself, Greek and non-Greek, but he only needed them in the main to perform secondary roles as the Macedonians bore the brunt of the fighting. His Successors were forced to use them in place of Macedonians, who now came to be just the elite core of most armies, greatly outnumbered by non-Macedonians.
Of necessity, mercenaries were now deployed in the main phalanx. According to Diodoros, Antigonos' phalanx at Paraitakeni comprised 9000 such men, in addition to 3000 Lykians and Pamphylians, 8000 mixed-race troops armed in the Macedonian manner (these apparently were a proportion of the 30000 mixed-race troops Curtius and Diodoros record Alexander having ordered to be trained while he was campaigning in India), plus 8000 Macedonians lent to him by the Macedonian regent Antipatros, an unusually large contingent for the times. Clearly the mercenaries who fought in such phalanxes were not traditional skirmishing peltasts. It is just possible that some mercenaries were being trained to fight in the Macedonian manner with the sarissa rather than Iphicrates' equipment, although there is no direct evidence for it, and the likelihood remains that the great majority were Iphicratean-style hoplites.
Because the Macedonians were the most proficient part of each Successor's army and also the hardest to replace, the Diadochoi had an incentive to use them sparingly. Alexander had used his Macedonians on numerous side actions in the course of his campaigns.Casualties were constantly replaced by yet more drafts from home, denuding the country of fighting men. Diodoros describes how Antipatros, the regent of Macedonia, could only call upon a mere 13000 Macedonians at the outbreak of the Lamian war in 323 BC because of the constant drainage of men eastwards. What was appropriate for Alexander was not for the Successors. They had to harbour their Macedonians for use in the pitched battles that ultimately decided all their fates. The likes of Leonnatos, Eumenes, Krateros, Antigonos, Perdikkas, Neoptolemos and several others all died in or as a direct result of pitched battles, and the few that did not, such as Ptolemy, Seleukos and Antipatros only owed their continued existence to fighting such battles successfully. In any case, such side-operations were increasingly rare - Asia had after all been conquered, the only opposition of note were the other Diadochoi (or Greeks fighting in a similar manner), and battles between them were normally decided in the open plains, not in mountain passes. If they needed troops to occupy mountain passes, they turned to more expendable men. Hence we see the faint return of the peltast. Diodoros 19.19.4 has this seemingly stray reference: Antigonos "selected the finest of his peltasts and divided the bowmen, the slingers, and the other psiloi into two parts to occupy the places that were narrow and difficult". The usage of the word peltast here comes as a complete surprise, since Diodoros until this point makes no mention of peltasts in Antigonos' army, and indeed, makes no mention of peltasts in the entire previous two volumes of his history, concerning affairs from Philip's time onwards.
Macedonian soldiers were trained in the use of both javelin and pike; there was no reason Greek mercenaries could not be trained to use both spear and javelins as the situation demanded. Such training would be extremely hazardous, since a mercenary had the option of leaving his current employer if service conditions were not to his liking, and training men who might one day fight on the side of your enemy might seem like a risky investment indeed. Antigonos evidently fought it was worth the gamble, since the very best of his mercenaries could apparently be used as peltasts.
It can hardly be coincidental that Antigonos had been given his command by Alexander as long ago as 333 BC; he might have been working with some of these mercenaries for many years since he had held it continuously for all that time: plenty of time to select the most loyal and train them up to the standards required to be able to fight as peltasts as well as hoplites. One might also consider that when Alexander was still alive there may have been no need to consider the possibility of his troops fighting for his enemies. Other commanders did not have this luxury of long service, and so it is perhaps not surprising we do not hear any more about such peltasts, although the sanctity of source material is just as likely to be the cause. It is also noteworthy that Antigonos' allotted sphere of operations under Alexander was the mountainous interior of present-day Turkey, where troops that could fight in both roles would have been especially valuable. Basic light-armed troops, psiloi, and the equivalents of traditional Greek-style peltasts, were generally readily available from native sources, but were of limited use in pitched battle. If Greek troops had to be single-role only, hoplites would have been preferred over peltasts given the importance of pitched battles. A troop type that couldn't pull its weight in such circumstances was of very limited utility. Antigonos had fought 3 battles against the Persians while Alexander pushed on ahead into the Persian heartland, and then later had to deal with a Kappadokian nationalist movement.
As Macedonians were seemingly no longer routinely being employed in their peltast capacity, it is possible they may have lost the ability to operate efficiently as dual-role troops. Certainly the later Hellenistic tactical manuals of Ailian, Arrian and Asklepiodotos, no doubt derived from Polybius' lost manual via Poseidonius, and incorporating information derived from works by early 3rd century generals like Phyrrus, make no explicit mention of any dual-role function for the soldiers of the phalanx. All is not as it seems however. According to Polybius, at least some elite Antogonid pikemen of the 2nd century were called peltasts.
If any troops in the later Antigonid army retained the ability to function in two roles, the 'peltasts', as elite troops, would be the obvious choice. This would explain the evident confusion in the late Hellenistic manuals describing Macedonian 'peltasts'. As Aelian puts it (2.8): "The peltasts have similar equipment to the Macedonian, but lighter: For they carry a pelta and light-weight arms, and spears shorter than a sarissa. This manner of arming appears to hold a middle place between that of psiloi and those properly called heavy infantry, being heavier than that of the light-armed and lighter than that of the heavy infantry, and for this reason most authorities place it among the light armed". Evidently some authorities Aelian had consulted considered the peltasts to be not light armed at all, but heavy infantry. A 'peltast' with a pike would indeed be a heavy infantryman, a hoplite; a peltast with a javelin would not - but would still be more heavily equipped than the psiloi. It is perhaps notable that the only times Polybius mentions 'peltasts' in the Seleucid army they are on one occasion described as leading an assault through a breach in a wall (10.31.11), and on the other as being 10000 strong (10.49.1). Elsewhere Polybius tells us that the elite portion of the Seleucid phalanx was 10000 strong and that most of them were called Argyraspids. It seems likely that these men were 'peltasts' in exactly the same manner Antogonid pikemen were 'peltasts' - they could be rearmed for certain missions. This would also neatly explain why the Hellenistic tactical manuals do not talk about how 'peltasts' are marshalled, nor how many there should be in the army (in contrast to the psiloi and phalangites), but make reference only to their equipment. If they were the same men the phalangites, they would never make an appearance in such deployment discussions, since they were already included - as hoplitai (phalangites).
Thureophoroi
It is after the Galatian invasion
in 279 BC that Greek troops carrying the Galatian shields 'thureophoroi', start to appear in the
Greek sources. They appear at first in citizen armies such as the Boeotian
league, but later in Successor armies as
well. Polybius records thureophoroi in a Seleucid context by 220 BC who may well
be mercenaries. While the
traditional citizen hoplite remained the backbone of many city-states' forces
for some time, others were evidently adapting to changing circumstances.
Corinth had yet to make any significant changes a generation after the invasion.
According to Plutarch, the Spartans continued using hoplites until 225 BC when
its troops, both citizen and helot, were converted into Macedonian-style
phalangites. One state that did not continue using hoplites for long was Boeotia. From inscriptional evidence they fielded citizen troops equipped as
both thureophoroi and hoplites until the 240s BC when the mixture changed to
thureophoroi and 'pelte' bearing
pikemen, such as their neighbours the Macedonians employed. What then was the
armament of these thureophoroi, and what was their tactical role? The Galatians
were swordsmen, but Celtic sword fighting does not appear to have been adopted
by the Greeks along with the thureoi. Representations of troops equipped with thureoi from
the Hellenistic kingdoms usually show them equipped with a single spear, the
vast majority are equipped with a single thrusting spear, longer than the bearer
is high.
Lacking a missile weapon, such troops had no more ability to skirmish than their
4th century ancestors. Yet as they lacked both (heavy) body armour and pikes,
they were not in the same class as phalangites when it came to close combat.
Such a jack-of-all-trades troop type would have been less than ideal in many
situations, and the search for improvements appears to have begun early. One
direction was to strengthen their combat ability by equipping them with heavier
equipment. "Thorakitai", that is troops wearing (heavy) body armour,
feature prominently in Polybius' accounts of the Achaean army, as distinguished
from both the pike phalanx and the light troops. These troops were frequently
deployed with the Illyrians, usually fighting between the phalanx and the light
troops. Thorakitai are most likely just armoured thureophoroi, and
representations of Hellenistic troops sometimes show spearmen with thureos and
mail; the mail being introduced as a result of either Roman or Celtic influence.Another possibility was to enlarge the size of the thureoi
so that it's protective value was similarly increased, albeit at the expense of
mobility and cheapness.
Euzonoi
Another significant piece of evidence is to be found in a passage in Plutarch describing the citizen troops of the Achaean league at the battle of Sellasia in 222 BC. He says they used "thureoi too narrow to cover the body, and spears (doru) much shorter than pikes. By which means they were skilful in skirmishing at a distance, but in a close fight had much the disadvantage". It is difficult to see how a thureophoroi equipped with a thrusting spear could skirmish effectively, but if this was replaced by a pair of javelins, this objection is removed. It only then remains to be explained how the word for spear came to be used rather than javelin: spears were the normal equipment of thureophoroi, although perhaps Achaeans made more use of rearming their troops with javelins than did others. Such troops, despite carrying thureoi, might have been unlikely to have been called thureophoroi if thureophoroi already had the widely understood meaning of a (spear-wielding) thureos bearer. Yet calling them peltasts might have also caused as much confusion to contemporaries, since as we have seen, that term was used of Macedonian pikemen who were (or rather, could be) temporarily rearmed with shorter weapons. The new troop type demanded a new name, and I believe that name, at least in Polybius, was the euzonos.
The word euzonoi (unencumbered, or lightly equipped; it originally had no military connotations) had been used to describe soldiers at least as far back as Xenophon ca. 400 BC, who could use the word of troops as diverse as psiloi and hoplites, so long as they were particularly nimble and active on their feet. But by Polybius' day in the 2nd century BC, the word had seemingly come to mean a separate troop type, since in his history we hear not only of euzonoi, but of troops "armed in the manner of euzonoi".19 The extent portion of Polybius' history never tells us what he means by arming in the manner of euzonoi, but in Polybius' account of the 3rd battle of Mantinea he refers to the Achaean euzonoi being defeated along with the Tarentines in the front line, where they are supported by, but do not include, the Illyrians and the thorakitai. The Achaean euzonoi were mercenaries by this date: in 208 BC the Achaean citizen troops had all been rearmed as Macedonian-style pikemen. Plutarch also describes the same battle in his Life of Philopoimen. Plutarch reports that "Machanidas and his mercenaries beat the javelinmen (akontistas) and Tarentines whom Philopoimen had placed in front". This would indicate that the euzonoi of Polybius and the akontistas of Plutarch are one and the same.
Polybius was a general in the Achaean army, and like Caesar, another historian-general, was never caught short for a technical word. For him euzonoi had a specific technical meaning when used in a military context, just as did the term 'peltast', even if he might use it in a non-technical manner as well. Later authors, divorced by time from the proceedings, but heavily influenced by classical authors of such as Thucydides and Xenophon, tended to use terms that reflected classical usage, not those of the times they reported. Hence the confusion of the late Hellenistic tactical authors such as Arrian and Aelian - men who knew from their classical education that a peltast was a skirmisher and struggled to understand that Polybius (or even Poseidonios, his late 2nd century tactical continuator) could talk about peltasts in other ways. It is particularly interesting to note that when Polybius does talk about peltasts in a non-Macedonian context, it is in a manner that easily implies pikemen who could also be javelinmen. I have already mentioned the Seleucid 'peltasts'; the Achaeans seem to have been the same. At 22.9.2-3, we read that in 188/7 BC Ptolemy had sent the Achaeans "six thousand sets of bronze equipment for peltasts (hopla chalka peltastika)". As previously noted, the Achaeans had adopted the pike by this stage. Bronze equipment (or even more tellingly, shields, as hopla is an ambiguous word) tallies best with pikemen, who used bronze shields as well as helmets and greaves, and citizens at that, since mercenaries usually provided their own gear. If the Achaeans as thureophoroi could rearm themselves as euzonoi, with javelins, there is no reason they could not still do so now that they were pikemen.
At the battle of Magnesia, the Achaeans participated as an allied force, led by Diophanes, fighting under Eumenes' command. Appian, calls the 3000 Achaean foot "peltasts" The Achaeans were drawn up next to a force of Cretan archers, Trallian slingers and other light infantry with javelins that defeated the Seleucid scythed chariots with their missiles. It is not said that the Achaeans assisted in this action but if they did, this would present no problem if they were using javelins rather than pikes.
Hellenistic pikemen, at least the most able of them, continued to be able to operate in a peltast-like capacity using javelins rather than shields, and that such pikemen were called 'peltasts', not because they carried a pelta (which they did, though the word peltophoroi would appear to be preferable in this context), but because of this dual-role peltast-like function. Other hoplites, whether classical or 'Iphicratean', were mostly replaced by either such pikemen, or else by 'thureophoroi' who differed from the hoplites they replaced only in the type of shield they carried - they were heavy infantry, not skirmishers. Like pikemen, thureophoroi could replace their spear with javelins to operate in a peltast-like capacity. Such troops were then not called peltasts however, at least not by contemporary sources such as Polybius, since peltast meant a pikeman. When operating as light infantry, they were no longer heavy troops, but belonged to the class of troops known as euzonoi, or light infantry, a word that Polybius sometimes uses in a narrow sense to mean such re-armed troops rather than light infantry in general.