Ancient army numbers

[Macedon]

I know this mate.

But when I read description of a battle, I get some picture of how many casualties could be sustained in that battle by each side. And in case of Gaugamela in all existing original (Ancient) descriptions of this battle, there are mentioned various "episodes" of this battle, in which some Macedonian units must have suffered considerable casualties. Just to mention Greek mercenary / allied cavalry being defeated on both flanks by enemy cavalry, or to mention Macedonian baggage train being attacked and largely slaughtered by Persian cavalry which before that broke through Macedonian lines (Arrian, III, 14). And many other similar episodes. It did not went completely smoothly for the Macedonians and many Persian units fought to the last man and did not collapse like their king and many other units.

Where? The only other place where many more casualties should be expected is in the Macedonian camp, if the few guards left put up resistance. The Thessalians and the left flank were hard-pressed, that did not mean that they sustained many (even more than a few) deaths. Wounds, certainly. In no place did the Persians break the enemy, there was a gap that is reported to have formed but that was not a break per se. There is no flight of Greeks. The fact that the Persians skirmished against the Greeks was a very wise tactic. Darius hoped to trap the infantry in the plains and encircle it with cavalry. Had he beaten the Greek cavalry he would have succeeded. Had he the time, this is what would have happened. This is why Alexander rushed to the attack. There was no way his cavalry could endure endless traditional cavalry engagements, eventually they would flee and the infantry would have been trapped, unable to ever reach the Persian foot and ensure victory as was the case at Issus.

But who is throwing the whole Greek historiography out of the window?

I am not for sure. I am basing my claims on Grek historiography - namely on descriptions of the battle from Greek historiography, which describe this battle in such a way that clearly disproves the casualty claims made by the same historiography (again it contradicts itself) - because we can see many episodes in the battle of Gaugamela, which must have produced considerable casualties on the Macedonian side.

Some of them were mentioned above.

Apart from that Greek historiography also tells us that some of Persian archers were armed in "great bows" - as they are called there - which could pierce Macedonian shields and armours. For example Mardian archers had such weapons at their disposal.

Did you notice the "could" part? I am not insisting that Alexander did not sustain more casualties, I also mentioned Diodorus. I claim that he COULD have sustained such few casualties. As for the Mardian bows, again I would like to see the quotes you refer to and I have to say I am extremely reluctant to accept that they would just pierce through the Macedonian shields.

Any proofs for this claim? That Ancient armies had casualty reporting systems?

By the way - if numbers were from casualty reports, they would not be so round - but detailed (for example 112 not 100 killed) and they would not contradict each other so much (Arrian - 100, Curtius - 300, Diodorus - 500, etc., etc.).

Many... Alexander had his royal ephimeris (something like records of the campaign) and also records were kept meticulously for many reasons. Each man would have been recorded, his rank, his pay, probably also his facial characteristics and things like scars (I have seen such reports for hellenistic conscripts and slaves). The Romans kept such records too. The Greek city states, in their local wars, had to give burial rites, inscribe the names of the dead etc. Apart from the issue of the reliability of these records, the thing is that they were not open to the public. Some historians wrote that they used them, at least what had survived... Do not forget that we have absolutely no first hand account of Alexander's exploits. Ptolemy's and Callisthenes' accounts do not survive... Unfortunately, we only rarely are informed of where the various authors found things, so I cannot with any certainty say that 100 is the number Ptolemy suggested and 500 this of Callisthenes... As far as I am concerned, Arrian says 100, Diodorus says 500, Curtius I simply do not like...

Please don't apply modern standards to Ancient historians.

I fail to see your point here... What do you mean? What modern standards? And what are these "modern standards" you are referring to? That they would often criticize other authors and sources is a fact. That they maintained that the truth should be their goal is also a fact. What is your objection?

I think accounts are much more frequently wrong than actual written reports / documents (but again I don't think that Ancient armies had something like casualty reports - considering that the main purpose of reporting casualties is to check how many reinforcements are necessary for each unit, and Alexander was incorporating to his army any reinforcements he could get, without paying much attention how many are "necessary" and how many are not "necessary" - IMO).

So maybe they had those casualty info from accounts of so called "witnesses".

No.. ancient armies were much better organized than you seem to believe. They had to account for the wounded and dead, they were expected to care for the survivors, the families of those fallen or rendered invalid in combat, they kept very careful track of payments, debts etc. The ancient world is much more complex and bureaucratic than what you seem to think. As for reports being deliberately or by mistake falsified, yes, they could. Yet, records is one thing and "reports" (official and unofficial) something different.