How was Alexanders army able to deal with the Persian archers?

[Conan]

Hey guys,

I know this is a bit out of EB time frame but I'm sure most peeps here have a good knowledge of this time period.

Through the number of engagments Alexander army had the army of Darius III how would his phalanx and cavalry delt with the number and I imagine good quality of Persian archers?

[Ca Putt]

IIRC we had such a discussion here some years ago. I think the "result" was that the combination of "heavy" arrow proof armor, thick shields and deflection through Pikes. In addtion to swift cavalry which has proven usefull against archers throughout the ages.

while a linothorax(no matter if actually linnen or Leather) may not be a good choice vs swords it's flexibility provides ample protection against arrows. As seen in EB the pikes form a sort of artificial forest, thin but constantly moving trees, the arrow is no bullet aka has a substancial length and is not lightnigh fast, thus random deflection is likely. An arrow which has lost it's momentum is unlikely to pierce a helmet or the shoulderpiece of a linothorax.
While this does not make them immune to arrow fire it provided sufficient protection to get a substancial part of them into melee with Sparabara and Hoplites where their superiority is more apparent.

At least that's how I see the matter.

[Titus Marcellus Scato]

The Macedonian phalanx had no other option than to march forward through a deadly hail of Persian arrow fire to reach the enemy front line. Most of the phalanx casualties came during the advance to contact, not the melee itself, although the numbers of wounded would far outnumber the dead. The Macedonians had little defence against arrows and slingshot, but once in contact the lightly armed and armoured Persians had little defence against the massed rows of pikes and would rout quickly.

Also, Persian archers and slingers were terrified of enemy cavalry and would rout as soon as it came anywhere near them. With mass panic communicating rapidly through the milling hordes of skittish light missile troops, thousands could be put to flight with a cavalry charge.

[Conan]

Does make you wonder why the Persians never really adopted some form of heavy infantry wholesale... Especially after their experience with Greek hoplites during the Greek-Persian wars. Although I suppose they simply employed them as mercenaries, which may have been quicker and/or cheaper than training there own men/units.

Mind you the way the Persian army was composed it had conquered a large chunk of the known world by this point and had kept the Ionian Greeks at bay for centuries. Their army as it was had not only conquered, but maintain the status quo and I imagine was not seen as needing re-forming until well Alexander came along and by that point it was too late!

I guess you also have to bear in mind that it wasn't a walk in the park for the Macidonian army either and that they very nearly could have lost their engagments with the Persian army. I imagine luck would have played a big part in the outcome also...

Suppose I'm answering my own questions as I carry on with this!

[seleucid empire]

Does make you wonder why the Persians never really adopted some form of heavy infantry wholesale... Especially after their experience with Greek hoplites during the Greek-Persian wars. Although I suppose they simply employed them as mercenaries, which may have been quicker and/or cheaper than training there own men/units.

Mind you the way the Persian army was composed it had conquered a large chunk of the known world by this point and had kept the Ionian Greeks at bay for centuries. Their army as it was had not only conquered, but maintain the status quo and I imagine was not seen as needing re-forming until well Alexander came along and by that point it was too late!

I guess you also have to bear in mind that it wasn't a walk in the park for the Macidonian army either and that they very nearly could have lost their engagments with the Persian army. I imagine luck would have played a big part in the outcome also...

Suppose I'm answering my own questions as I carry on with this!

They had some heavy infantry didn't they? Their Immortals would have had good armour and carry swords/spears as well as bows but they were just inferior to the Greek and Macedonian phalanx so it doesn't show.

I'm gonna take a wild guess here and speculate that they realised the advantage of heavy infantry but they probably knew that they could never hope to match the Greeks so they improved other parts of their army to level the field (e.g. Their cavalry) and hired Greek Mercs to supplement their army.

Also in the east I'm guessing heavy infantry isn't as effective as large amounts of cavalry or archers?

Actually for most of ancient history, the east seems to have been dominated by cavalry and missiles. Think of the bactrians, Parthians, Sassanids,

[Arjos]

As mentioned, he used swift tactics with his cavalry, but let's not forget about Kretikoi and Peltastai, essential for those manouvers...
Although what really was revolutionary, both with Philippos and Alexandros, were siege engines and torsion weapons: they brought siege warfare to a complete new level...

Persians had heavy infantry (both persian and from subjects, particularly good were the Sacae), these troops were actually successful against hoplitai at Marathon, for example. But as pointed out, eastern landscape, worked perfectly for mounted warfare...
But most of all, the Persian empire, was coming from a series of prolonged rebellions (Egypt, aided by Greeks most of the time, was a perennial drain of resources) and inter-satrap conflicts: as with many large polities, it was collapsing on its own weight (lack of strong rulers; court schemes and assassinations; satraps fighting eachother, either in rebellion or to gain greater favour from the Shahanshah). Also Darius III, himself wasn't exactly the best military leader one could hope for...

So in the end, taking Alexandros' campaign, he could field more heavy infantry, while the Persians had to rely on light levies and mercenaries. And Darius for one reason or another, failed to exploit his cavalry to their fullest and/or Alexandros was just a better tactician, especially of mounted warfare...

[Ca Putt]

The Acheamenid persians made great use of Greek mercenary Hoplites and also employed similar troops in smaller numbers.

Concerning the reluctance to "switch" to heavy infantry on the side of the persians probably roots in very different circumstances:
(in no particular order)

being a heavy infantry man is not pleasant. - You have to carry a heavy armor on foot, engage your enemy in melee and in case the battle turns sour, it's unlikely you'll get away, because your slow. When you're going to war you'll either want a horse(to get away quicker) or a bow(to avoid melee), unless some code of honor prohibits such cowardly conduct.

Tradition - the Bulk of the Persian Empire had either equestian or Archery Tradition, which helps a lot with recruitment of either. And as explained above and "shown"* in many games, If you can get good cavalry and archers you'll not tell your sheperds and lower nobility to get a shield and off of that horse. And the results would be subpar at best. A noble who has fought from horseback for X generations will mostlikely not make a very good hoplite. In antiquity a great part of the military education was through the father(or uncle or grandfather) and like today a boy who went hunting with his dad is morelikely to become a good marksman/soldier than one who's dad went fishing(something that is not required in todays armed forces) with him. changes like this would take several generations to yield superior heavy infantry

Population structure - While incorporating plenty large cities the Predominant recruitment pool of persians probably was based on cattle-droving seminomads OR people who have just given up this Lifestyle one or two generations ago. Some historians may actually bring up the ethernal fight between Cain and Abel, Something I'd be carefull with however. Not to say Persians had less Cities, they just had more other stuff, whereas Greece basically consists of rocks, water and settlements that consider themselves cities,... well and Tessaly.
In essence city dwelling farmers make "good" Heavy infantry, seminomadic stockbreeders make "good" archers or Cavalry(depending on wealth and terrain).

Terrain - "Persia" is mostly arid or mountainous there also are fertile regions and in antiquity there also were some forests. but most of the time you have perfect conditions for Cavalry and archers. Greece on the other hand is mostly a coastal thing with valleys placed conveniently to fight a pitched battle or two, neat for archers and shielbearers, but terrible for cavalry.


*overly pronounced

[Basileus_ton_Basileon]

IIRC we had such a discussion here some years ago. I think the "result" was that the combination of "heavy" arrow proof armor, thick shields and deflection through Pikes. In addtion to swift cavalry which has proven usefull against archers throughout the ages.

while a linothorax(no matter if actually linnen or Leather) may not be a good choice vs swords it's flexibility provides ample protection against arrows. As seen in EB the pikes form a sort of artificial forest, thin but constantly moving trees, the arrow is no bullet aka has a substancial length and is not lightnigh fast, thus random deflection is likely. An arrow which has lost it's momentum is unlikely to pierce a helmet or the shoulderpiece of a linothorax.
While this does not make them immune to arrow fire it provided sufficient protection to get a substancial part of them into melee with Sparabara and Hoplites where their superiority is more apparent.

At least that's how I see the matter.

I'll supplement Ca Putt's points with one of my own.

Do note that arrows do not occupy a thin cylindrical space as they travel through the air; they tumble, bend, flex and spin in an area roughly the shape of a rugby ball- abit far larger. Imagine hundreds of rugby balls each 2 feet in length tumbling through the air, the likelihood that they get caught in the brambles of pikes or tree branches is now considerable. Also, volley-fire is never accurate anyhow. It's a matter of quantity over quality.

[athanaric]

Good points there.



Terrain - "Persia" is mostly arid or mountainous there also are fertile regions and in antiquity there also were some forests. but most of the time you have perfect conditions for Cavalry and archers. Greece on the other hand is mostly a coastal thing with valleys placed conveniently to fight a pitched battle or two, neat for archers and shielbearers, but terrible for cavalry. Also, the area of the Persian Empire is a continguous (and large) landmass, even though very variable in climate and landscape. The Greek motherland OTOH practically forces its inhabitants to rely on infantry warfare, because fertile plains, while they exist, are limited in extension and have to be utilized for agriculture of all kinds (and it's phantastic to see what you can grow in places like the Eurotas valley or the Argive plain - basically everything, except rice). Not much space for horse herds of sufficient quality or quantity there. The mountains are either forested or used for other livestock or wine, olives etc (curiously, nowadays, most of them are covered with maquis or garrigue. Probably a result of over-exploitation). Also, for most regions in Greece, ships are a much faster and more efficient means of transportation than horses.


Furthermore, the formation of small (city) states* is favoured by the Greek topography, and heavy infantry is a typical military element of city states.

*Polis doesn't necessarily indicate a city.

[seleucid empire]

Furthermore, the formation of small (city) states* is favoured by the Greek topography, and heavy infantry is a typical military element of city states.

*Polis doesn't necessarily indicate a city.

This leads me to my own question.

The Greeks and Romans both had citizen armies which meant both nations were militaristic at heart.

So how come the Greeks never invented heavy sword armed infantry like the Romans and instead created the more complex phalanx? They seems to have skipped an easier option. Was it something to do with the fact that they didn't come in contact with the scutum shield?

And would the result have been the same at Thermopylae if a roman legion was there instead of the Greek phalanx

[Basileus_ton_Basileon]

The thing is, they were largely similar, at least initially. The Romaioi started off with very similar traditions as the greeks due to their Etruscan origins, along with the greeks along the south. Their difference were that they had experienced Keltoi migrations earlier than the greeks did, along with their rivalry with the samnites. From the former they learnt to use maille (flexible and easily recyclable/reusable compared to the thorax and cuirass) and the thueros (a lighter shield compared to the aspis, but with similar degree of protection, though less durable). Fighting the Samnites in their mountains gave rise the need for a more flexible formation than the hoplite line.

Remember that the greek hoplite phalanx had it's emphasis in protection because the men are all citizen farmers, they have much to lose if they're dead. Also to answer your question on Thermopylae: The Romaioi would be slaughtered, their republican formation's strength lies in flexibility, not raw defence. Their linen-clad thueros lacks the durability that an aspis has, and their kopis/xiphos/gladius simply does not have the reach that a dory has. Note that the hellenes also wielded the sword, as a sidearm after even the butt-spike of their dory has broke. In the hot gates, the hoplite's inflexibility and prone to sudden flanking is simply negated by the narrow valley.

[seleucid empire]

The thing is, they were largely similar, at least initially. The Romaioi started off with very similar traditions as the greeks due to their Etruscan origins, along with the greeks along the south. Their difference were that they had experienced Keltoi migrations earlier than the greeks did, along with their rivalry with the samnites. From the former they learnt to use maille (flexible and easily recyclable/reusable compared to the thorax and cuirass) and the thueros (a lighter shield compared to the aspis, but with similar degree of protection, though less durable). Fighting the Samnites in their mountains gave rise the need for a more flexible formation than the hoplite line.

Remember that the greek hoplite phalanx had it's emphasis in protection because the men are all citizen farmers, they have much to lose if they're dead. Also to answer your question on Thermopylae: The Romaioi would be slaughtered, their republican formation's strength lies in flexibility, not raw defence. Their linen-clad thueros lacks the durability that an aspis has, and their kopis/xiphos/gladius simply does not have the reach that a dory has. Note that the hellenes also wielded the sword, as a sidearm after even the butt-spike of their dory has broke. In the hot gates, the hoplite's inflexibility and prone to sudden flanking is simply negated by the narrow valley.

Thanks, you answered my questions very well. Although I did not realise that the roman legion was so outclassed by the Greeks in terms of defence. I knew the phalanx provided much better defence but I always thought a roman legion was solid enough to also defend Thermopylae successfully.

[Basileus_ton_Basileon]

Besides adapting the thueros, maille and the manipular formation earlier than the greeks (which didn't bother until the galatian invasion), the Romaioi also had the willingness to send more of their people into battle. Look to Pyrrhos' invasion, the Epirote king was more than a match for the Romaioi, both in strategy, tactics and equipment. The Romaioi simply responded by literally man-spamming until they won out. I'm sure if its the Romaioi at Thermopylae, they would not even bother use the place as a bulwark; they would simply out grind the persian warmachine in manpower. Worked on Pyrrhos; worked on Hannibas; worked on the Sweboz migration. If you run out citizen soldiers? spam out the urban poor. Not enough? enfranchise the provincae populace.

if you've played as the Romaioi in EB, You'll get where I'm getting at ;)

Sorry for digressing from the topic, oops.

[seleucid empire]

Besides adapting the thueros, maille and the manipular formation earlier than the greeks (which didn't bother until the galatian invasion), the Romaioi also had the willingness to send more of their people into battle. Look to Pyrrhos' invasion, the Epirote king was more than a match for the Romaioi, both in strategy, tactics and equipment. The Romaioi simply responded by literally man-spamming until they won out. I'm sure if its the Romaioi at Thermopylae, they would not even bother use the place as a bulwark; they would simply out grind the persian warmachine in manpower. Worked on Pyrrhos; worked on Hannibas; worked on the Sweboz migration. If you run out citizen soldiers? spam out the urban poor. Not enough? enfranchise the provincae populace.

if you've played as the Romaioi in EB, You'll get where I'm getting at ;)

Sorry for digressing from the topic, oops.

I suppose thats true, although i wonder if rome actually had the manpower to outspam persia (not that they need to, having higher quality infantry)

Hmmm, Im not sure about spamming in Roman campaign, I can usually get around 3 stacks early game, but then my city development gets pushed back by a decade (cause I use very high taxes whenever I can and I never enslave, only exterminate LOL). But I see where your coming from. When playing other factions, I dont have a chance in hell of fielding three stacks as early as when I do playing Rome

[Flavius Merobaudes]

I suppose thats true, although i wonder if rome actually had the manpower to outspam persia (not that they need to, having higher quality infantry)
Based on the sheer numbers and vastness of the Persian Empire, one would have concluded that the Romans could impossibly have outspammed the Persians. But I hope you won't mind me to disagree with you there.
From all sources we have we can be sure that the Persian army of Xerxes was vast. Numbers and estimations differ in quite a wide range, but after all they were not innumerable. With a large proportion of the population mobilized and ready for combat, the Romans might possibly have outnumbered the Persian. Take into the equation the attrition and generally the difficulties an invader would have to face in enemy territory, and you might come up with some clear advantage for the defenders - espacially in a protracted war.
The Persian Empire was a its high point under Xerxes, but it could never afford to direct its force against one single foe over a longer period of time. After all, keeping the empire together as it was, consumed the major part of its resources. Thus, a single and all but large invasion was possible, but nothing in the sense of a total war - or else the empire would have gotten into difficulties. One example for that might be the return of the Shahanshah leaving his general Mardonios behind to manage the protracted war on a smaller scale. The Roman concept of war on the other hand comes much closer to what we might call a total war.

I apologize for speculating too much here, but I take your question as speculative in itself. Most probably there is someone with a deeper insight into the topic who can tell us more.

Edit: It is quite interesting to see, how a conversation that started with "Alexander's army vs. Persian archers" can drift off to an imaginary "what-if?: Romans against Persians almost 2 centuries earlier"...

[Basileus_ton_Basileon]

I concur. Pound for pound, number on numbers, the Romans cannot possibly outspam the Persians. But they don't need to.

With such a vast empire to protect and defend, it is impossible to throw everything at the Romaioi. All the Romaioi need to do is spam enough to make the Persikoi believe that they're not worth the man-spam to crush. The persikoi will withdraw, and the Romaioi will 'win'.

As for Alexandros' army against archers, practically everything the phalangitai uses have a precautionary purpose against archers (look at the previous posts). it's no surprise that the arrow rain would have minimal effect on them. That being said, it is Alexandros' genius and his professionally integrated army that won his empire. The Makedones simply do not have even the fraction of resource and manpower to man-spam the persians in an invasion.

[I_damian]

I suppose thats true, although i wonder if rome actually had the manpower to outspam persia (not that they need to, having higher quality infantry)

The Romans were at war with "Persians" (or their successors, like the Parthians) for around 5 centuries on and off... You can see the outcomes, you don't need to imagine. The information is there.

[Flavius Merobaudes]

The Romans were at war with "Persians" (or their successors, like the Parthians) for around 5 centuries on and off... You can see the outcomes, you don't need to imagine. The information is there.
Forgive me being so honest, but that is totally incomparable to what we are talking about - at least if I understood seleucid empire's question correctly.

We were talking about what might have been if the Achaemenid Persians would have faced the Roman Republic instead of an alliance of Greek poleis in an invasion. This was a one-sided and locally confined operation.
You try to compare it to the clash of two empires half a millenium later? Really? The Roman Empire was fundamentally different from the res publica of earlier times. This difference is even more evident between the Achaemenids and the Parthians. Just look at social and political structure, look at populations and economies, and therefore military capabilities. Look at advances in science and technology, and in case of the Parthians look at the ethnic change that took place - with all its consequences.
What you said is just as much BS as comparing the Roman Empire to today's Italy would be, or comparing the 13 colonies to the modern USA.

But I grant you that this is not really your fault but a widespread misconception. We humans like to attach items to certain categories, and we tend to emphazise similarities over differences. So there's no need to take this personal if I say that there is not a shred of truth in your comparison.

[I_damian]

Forgive me being so honest, but that is totally incomparable to what we are talking about - at least if I understood seleucid empire's question correctly.

We were talking about what might have been if the Achaemenid Persians would have faced the Roman Republic instead of an alliance of Greek poleis in an invasion. This was a one-sided and locally confined operation.
You try to compare it to the clash of two empires half a millenium later? Really? The Roman Empire was fundamentally different from the res publica of earlier times. This difference is even more evident between the Achaemenids and the Parthians. Just look at social and political structure, look at populations and economies, and therefore military capabilities. Look at advances in science and technology, and in case of the Parthians look at the ethnic change that took place - with all its consequences.
What you said is just as much BS as comparing the Roman Empire to today's Italy would be, or comparing the 13 colonies to the modern USA.

But I grant you that this is not really your fault but a widespread misconception. We humans like to attach items to certain categories, and we tend to emphazise similarities over differences. So there's no need to take this personal if I say that there is not a shred of truth in your comparison.

He asked if Rome had the manpower to outspam Persia. The answer is no.

[Basileus_ton_Basileon]

oh tish and give the poor man a chance. He just needed an excuse to prolong the thread discussion.

[seleucid empire]

I guess I should have made it clear that I was talking about the Achaemenid Persians

[Ca Putt]

Simple answers kill the discussion :(

[Marcus Darkstar]

Hey guys,

I know this is a bit out of EB time frame but I'm sure most peeps here have a good knowledge of this time period.

Through the number of engagments Alexander army had the army of Darius III how would his phalanx and cavalry delt with the number and I imagine good quality of Persian archers?


I'm not as versed as these fine fellows in Alexander's campaigns but didnt he have contingents of Cretan Archers? I know he had no where near the numbers of the Persian Archers but Alexander did have his own...

That said wasnt most of Daruis's Persian archers using a simplier bow not the compound bow which had only the range of around a hundred meters? Aint a big distance to close wtih calvary and heavy infantry. Them being peasant archer levies i doubt the average persian all had compound bows... I know better persian troops like the horse archers etc used them because their the only way you can have effective horse archers but i would give them a grade far above levies..

[moonburn]

the siege or alesia aqua sixtae the romans went on the defensive and performed great in those roles pretty well so the romans would have take the hell gates as a defensive stand just as the greeks did because it made sense it gives them time to gather more men

as for their sucess it depends alot the roman troops quality always start as zerglings if they didn´t men like africanus wouldn´t loose so much time training new recruits before going against the lusitani or the numantians

what i mean is that their equipment is the same but the troop quality varies alot depending on the quality of it´s leading men and the experience of the men composing the legions

the romans went on an atriction war with hannibal because they where out of "decent" troops and didn´t want to banalise their troops wich would have costed them their allies in italy

there´s a reason why romans put so much enphasis on their vitality and manhood without their qualities their equipment counted for litle and they knew it thats why cato and so many of the bonii where against the reforms that sulla the grachus brothers or cesar defended

[Ca Putt]

A problem I see for Pre marian Romans would be their "Campaign"-attutude towards formation. Thus they put their "lings" in the front row, while this is an excellent idea when you're constantly waging war and anticipate a certain amount of casualties it's Illsuited for "last stand" battles as Thermopylae.

While I'm pretty sure Cammilian Triarii would have preformed similar to the Greeks(like duh) and I would reckon Polybian Principes would fare OK, I'm pretty sure Republican Hastati would brake and bereft of manoeuvrebility they would go running INTO(rather than being able to retreat through their lines) the Princeps clinging to their shields, crying for mercy etc. which imho would significantly hurt the Principed morale, now being easier to brake themselves. While I consider Polybian Triarii to be inclined to get out aswell, Cammillian ones may have tried to hold out a la Leonidas. However one has to remember that:
a) these men have just witnessed their comrads flee, unlike the spartans who fought in the frontline and probably did not care so much about the Thebans, Thespians etc. as the Triarii would about their sons in law, younger brothers, neighbors etc.
b) with most of the "heavies" gone the supply of "pushers" on the roman side would have deminished to the point where the Persians would be able to just push them into the sea/against a wall.

It is to note however that the battle was not actually won, so "doing good" means to kill a lot of persians and holding out "till death" and "failing" would mean to break before killing many persians and being considered a minor inconvenience by Xerxes.

Thus I think that while a regular Army set up would result in "failure", rearrangeing ranks would let them fare "about as good" as the Greeks.

[Marcus Darkstar]

A problem I see for Pre marian Romans would be their "Campaign"-attutude towards formation. Thus they put their "lings" in the front row, while this is an excellent idea when you're constantly waging war and anticipate a certain amount of casualties it's Illsuited for "last stand" battles as Thermopylae.

While I'm pretty sure Cammilian Triarii would have preformed similar to the Greeks(like duh) and I would reckon Polybian Principes would fare OK, I'm pretty sure Republican Hastati would brake and bereft of manoeuvrebility they would go running INTO(rather than being able to retreat through their lines) the Princeps clinging to their shields, crying for mercy etc. which imho would significantly hurt the Principed morale, now being easier to brake themselves. While I consider Polybian Triarii to be inclined to get out aswell, Cammillian ones may have tried to hold out a la Leonidas. However one has to remember that:
a) these men have just witnessed their comrads flee, unlike the spartans who fought in the frontline and probably did not care so much about the Thebans, Thespians etc. as the Triarii would about their sons in law, younger brothers, neighbors etc.
b) with most of the "heavies" gone the supply of "pushers" on the roman side would have deminished to the point where the Persians would be able to just push them into the sea/against a wall.

It is to note however that the battle was not actually won, so "doing good" means to kill a lot of persians and holding out "till death" and "failing" would mean to break before killing many persians and being considered a minor inconvenience by Xerxes.

Thus I think that while a regular Army set up would result in "failure", rearrangeing ranks would let them fare "about as good" as the Greeks.

It should be noted from what i've read that experienced Roman generals like Africanus sometimes forgone the traditional manipular formations (specially having the youth up front etc) Forgoing massive reserves of replacement men to create a stronger main battle line. The 2nd Punic wars did force the romans to adopt new tactics.

[Miaow]

It should be noted from what i've read that experienced Roman generals like Africanus sometimes forgone the traditional manipular formations (specially having the youth up front etc) Forgoing massive reserves of replacement men to create a stronger main battle line. The 2nd Punic wars did force the romans to adopt new tactics.

While the manipular formation was in many instances a boon to the Romans, it was a main cause of their defeat at Cannae. The Roman narrow, deep formation made it easy for the numerically inferior Carthaginians to envelop them.

On the topic of Greeks against Persians, let's not forget that the Persians initially defeated the Greeks they met in Asia—the Ionian, Aeolian etc colonies—with relative ease, to the extent that contemporary Greek sources insist that, prior to Marathon, the Greeks essentially pissed themselves with fear at the idea of fighting Persians. That's why so few Greeks were willing to help Athens with the first invasion; only the Plataeans, who would have been enslaved by the Thebans without Athens, and the Spartans, who feared dishonour more than death, were willing to come (and only the Plataeans were there on time).

Indeed, the whole reason that the Persians were attacking Athens wasn't that they were horrible evil people intent on enslaving the "free world", but that Athens had supported its Ionian colonies in rebelling against the Persians. The Persians had crushed that Greek rebellion, and wanted to take revenge on what they saw as a foreign power meddling in their internal affairs. Well, they also wanted to conquer the whole world too, but the reason they targeted Athens when they did was that Athens had been unsuccessfully attacking them.

As to why the Persians went from beating the snot out of hoplites to having the snot beaten out of them by hoplites, one of the major reasons was cavalry—specifically the logistics of cavalry. The descriptions of some EB units reflect that effective cavalry required rather alot more horses than men, and horses are difficult at best to transport by sea. Moreover, Greece being Greece, it was very difficult for the Persians to resupply horses locally. This limited the ammount of cavalry that could be deployed in Greece, and made what cavalry was deployed very vulnerable to attrition. In the second invasion, the Persians didn't actually suffer a land defeat until well after their fleet had been beaten and the Shahanshah had left. At that point, they'd lost the capacity to bring significant ammounts of supplies or reinforcements from Asia (even assuming Xerxes had them and was willing to run the bill up even higher on what was probably the most costly operation of Achaemenid history).

The Persian military system relied heavily on cavalry; the role of the Sparabara was to form a shield wall, which was effective against opposing archers and allowed them to hold off less disciplined troops, but they weren't meant to go toe to toe with heavy infantry or hold off shock cavalry. The best defence of both sparabara and archers against enemy cavalry was the Persian cavalry's superiority. Looking through the known equipment lists of the Persian cavalry, we see maces coming up—in EB terms, AP weapons making them heavy infantry killers. Add in their bows which would have enabled the cavalry to manoeuvre and shoot the vulnerable flanks and rear of a phalanx. Alexander removed that superiority of cavalry when he came along with his even heavier cavalry, at a time when the social class providing the core of the Achaemenid cavalry was in crisis.

I wouldn't say the Persian "Immortals" were inferior to the Greek/Macedonian heavy infantry. Certainly, the Greeks/Macedonians did not make that claim. However, the "Immortals" were an elite unit, a small part of the Persian armies, whereas almost all of Hellenic armies were capable of slugging it out in a prolonged melee. Even when/if the Persian elites defeated the units in front of them, they couldn't be everywhere and the battle could still be lost—indeed, frequently was (c.f. Mardonios and his guards making a last stand while their army routed).

In Alexander's campaigns, the peltastai would have played an important role against archery as well—with shields and some body armour, open order infantry could have drawn considerable ammounts of arrows and still taken very light casualties.