What was the reason that Alexander the Great succeeded in overthrowing the Persian empire?

Is it possible that the key reason was that the people of Persia decided not to defend against Alexander so he could overthrow the strong Achaemenid dictatorship and capitalism?

(it seems this policy reiterated several times for example at the time of Arab invasion and Islamic revolution)

  • I'm not very well acquainted with this area of history, but certainly the Persian Empire during Roman (Republican and Imperial times) was highly disjointed and almost continuously marred by faction and infighting. Some of the terrain can be considered quite inhospitable for foreigners (certainly to the Romans, even though they conquered large areas of it temporarily), though not of course the Arabs! Naturally, the obvious factors like Macedon's warlike culture and certain military innovations helped greatly, not to mention Alexander's personal military genius, leadership, and charisma!
    – Noldorin
    Dec 18, 2013 at 0:47
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    – DVK
    Dec 23, 2013 at 0:29
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    This question is so old, that even Machiavelli already answered it in his "Prince"! Aug 21, 2019 at 23:34

2 Answers 2


To a large extent both Alexander and his father were inspired by the Ten THousand, as well as the Greeks' dramatic victories against the invasions by Darius and Xerxes.

In these campaigns the Greek heavy hoplite infantry had proved itself more than a match for the best that the Persians could muster. Once united under the Macedonian mantle, a force of sufficient size to contemplate overthrowing the Persian empire could be contemplated.

Although the spear is usually listed as the hoplite's primary weapon, this is misleading. The hoplite shield was cleverly built to both enable the wearer to rest it on his shoulder while covering his leftward colleague, or to wield it as a very effective weapon. Due to the manner in which it strapped onto the wearer's forearm, it was easily maneuvered by a hoplite both as a ram to knock his opponent over, and as a blunt knife to deliver a severs blow from it's edge. Although less maneuverable than the later Roman maniple, the phalanx was a tactical battlefield unit which the Persians simply were unable to handle without overwhelming numbers.

With the how dealt with , now consider the why. As much as anything, I believe it was to prove his worth to his father, and because he could.

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    +1 for mentioning the ten thousand, it always made me wonder why Alexander needed 55000 to do what they did with ten.
    – Jeroen K
    Dec 18, 2013 at 7:29
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    @JeroenK: The Ten Thousand only marched there, won one battle, and marched back. Alexander was more ambitious. Dec 19, 2013 at 0:02
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    @JeroenK: The ten thousand showed "it could be done." So Alexander took 55,000 to make sure he could do it.
    – Tom Au
    Dec 19, 2013 at 15:01
  • @Jeroen K the ten thousand were just part of one of the armies during the persian civil war
    – Hao S
    Nov 2, 2018 at 3:37
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    @FelixGoldberg: Likely true - but as the fate of losing armies, and even parts of losing armies, has traditionally been that of the Ephramites who attacked the Gileadites commanded by Jephthah, just surviving to march home was a major accomplishment. Mar 9, 2020 at 9:52

At the time of Alexander, the Persian Empire was an unstable empire whose pieces were falling into the hands of satraps, or local lords. One of these satraps, Bagaos, killed several kings of Persia before one of his "puppets," Darius III managed to kill him. Hence the Persians were far from united against Alexander, although they managed to field impressively large armies.

Darius II was not a particularly capable commander, who was unable to lead his admittedly inferior, but much more numerous troops against those of the highly talented Alexander, at the battles of Issus and Arbela. Nor was he able to attack Alexander during his seven month siege of Tyre, between the two battles.

Darius fled each time, and after Arbela was assassinated by his cousin Bessus, who proclaimed himself King, but was captured and executed by Alexander as a rebel.

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    Losing to a genius doesn't make one incompetent. The choice and abundance of adjectives in the Wikipedia article seems to indicate a decided bias against Darius, so one can't take it's conclusions as definitive. Dec 19, 2013 at 2:43
  • @PieterGeerkens: He fled the battlefield at both Issus and Arbela. Very few generals do that, and the ones that do get reputations for cowardice. He was also assassinated by his own cousin. He may not have been totally "incompetent" (he had a few successes) but he was a "failure" by most standards.
    – Tom Au
    Dec 19, 2013 at 17:50
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    For every conflict I check, only the losing commander flees the battlefield. It doesn't seem so clear to me that Darius fled without reason from either battle, given the personal bravery he had already demonstrated prior to becoming Emperor. Dec 20, 2013 at 1:13
  • @PieterGeerkens: I didn't say he retreated with his troops. The wiki article says he abandoned his equipment and his army. And the OP's question text is more along the lines of "What did the Persians do wrong?" than "What did Alexander do right?"
    – Tom Au
    Dec 20, 2013 at 2:40
  • @TomAu mostly the persians never made good heavy infantry units like the Greeks did, time and time again persian spearmen are beaten by fewer numbers of greek hoplites 2) fighting Alexander at Granicus -Memnon of Rhodes advised a scorched earth policy 3) fighting Alexander at issus 3a) better organization of the battle at Issus 3b) keeping a reserve of elite troops beside the king at issus at all times 3c) preparations for a potential defeat at Issus -there was none Darius's family and the royal treasury was captured a great loss of coin and prestige 4) Keeping a reserve elite force
    – Hao S
    Nov 2, 2018 at 3:55

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