Alexander’s Impossible Conquest Explained

0:05 The conquest of the Achaemenid Empire by the Greek forces of Alexander III

0:10 of Macedon is rightly perceived as one

0:12 of the most important events in world history.

0:16 Leading a highly efficient and innovative military force,

0:19 the young Macedonian general managed to conquer the largest

0:22 superpower the Earth had ever seen up to that point.

0:26 Many scholars have tried to answer

0:29 the question of why Alexander achieved this feat.

0:32 Sometimes the role is attributed to Alexander’s strategic

0:36 genius or to the supposed incompetence of his rival, Darius III of Persia.

0:42 The truth, as with any grand-scale military endeavour,

0:45 lies in a convergence of factors-

0:48 from the legacy Alexander inherited from his father Philip,

0:51 to the structural weaknesses of the Persian Empire,

0:54 to Alexander’s own remarkable capacity for military and political improvisation.

1:01 Background Factors: The first aspect that led

1:02 to the Alexandrian onslaught through Iran

1:04 has very little to do with either Alexander or his rival, Darius III.

1:09 That factor is simply the background of the states and societies in which

1:14 both rulers grew up before their titanic clashes at Issus and Gaugamela.

1:20 Alexander, while undoubtedly a military mastermind,

1:22 could not have achieved his goals without the legacy of his father,

1:26 Philip II of Macedon.

1:28 Philip was both a seminal military reformer and a shrewd diplomat,

1:33 points which we have discussed in our previous videos

1:37 and on our members-only series on the grand statesman.

2:23 When Philip came to power,

2:25 Macedon was under threat from the Illyrian kingdoms to the north and was,

2:29 at best, a secondary power in Hellas.

2:32 His military reforms with innovations such as sappers and siege engines,

2:36 as well as formalising the use of the long-spear known as the Sarissa,

2:41 turned the kingdom into a powerhouse in Greece.

2:44 He also managed to either annex or vassalise the whole

2:48 of Greece through military campaigns and the League of Corinth;

2:52 his whole military career in the second half

2:55 of the 4th century BCE was devoted to this affair.

2:58 In addition, Philip also had plans for attacking Persia,

3:02 and had already sent some preliminary contingents to Asia

3:06 Minor that Alexander could use when he began his operations.

3:10 Thus, Alexander inherited a strong military from his father,

3:14 one with experience and strategic cohesion.

3:16 In addition, the Greek allies of the Macedonians

3:19 provided him with both security on his southern

3:21 flank in Hellas and additional military personnel

3:25 that contributed to his success in Persia.

3:28 If we turn our eyes to the east,

3:31 we will find that Darius III faced a trickier situation to manage,

3:34 for the Achaemenid Persian empire was less stable than it had

3:38 been under Darius I and Xerxes in the 5th Century BCE.

3:42 Our sources about 4th-century Persia are scarce,

3:45 and often only Greek in character,

3:48 with the usual anti-Persian biases that imply.

3:51 But some information reveals the fragmented nature of Persia at the time.

3:57 Before Darius, the previous Shahanshah was Arses,

4:00 who seems to have ruled only for two years, 338-336.

4:04 He was allegedly under the control of a eunuch called Bagoas,

4:09 but this might be a fanciful tale

4:11 by the Greeks who wished to denigrate the Achaemenids.

4:14 Before him, Artaxerxes III ruled for about 20

4:17 years but had to deal with various revolts, including one in Egypt,

4:22 which had been independent of Persia for almost six decades.

4:26 His own father, Artaxerxes II,

4:28 also had to fight against his brother Cyrus for control of the throne,

4:32 where the Athenian soldier and writer Xenophon served,

4:36 later recording the experience in his Anabasis.

4:40 Thus, the political environment was rather unstable

4:43 by the time Darius came to power.

4:46 The young Shahanshah is often unfairly portrayed

4:48 in the sources as a coward or a weakling, but the truth is that he faced a far

4:55 harder context to contend with once he came to power.

4:58 Political success is often just as much

5:00 about circumstances as it is about skills,

5:02 and in the case of Darius, he inherited a far less robust empire than Alexander.

5:07 The Greek general had a strong foundation to build upon,

5:11 and he used that to his utmost advantage,

5:14 whereas Darius had to contend with what he had.

5:17 Military Factors: Besides the background

5:20 factors which gave Alexander an advantage,

5:23 there was also the most fundamental of aspects; that of military innovation.

5:27 Here, the importance of Alexander’s capacities as commander and tactician

5:32 came to the fore on more than one occasion.

5:35 The Greek army, which marched into Asia Minor in 334 BCE,

5:40 was a flexible and well-trained military machine.

5:43 Among its ranks lay Greek troops working as both hoplites and peltasts,

5:48 as well as experienced mercenaries from the Balkans.

5:51 The Macedonians, especially the Companions who served with Alexander,

5:56 were also from aristocratic families that had risen

5:58 through the ranks on the basis of their talent,

6:01 enabling them to devise masterful military strategies.

6:05 Other innovative specialist units,

6:07 such as the hypaspists, who had light-infantry capabilities,

6:10 also provided the young king with flexibility on the battlefield.

6:14 In addition, Alexander’s pezhetairoi were defined by their use of the Sarissa,

6:19 an innovation that enabled greater control over how battles unfolded,

6:23 thanks to the power of distance.

6:26 This is most evident in the battle of Gaugamela in 331 BCE,

6:31 where Alexander’s ability to use all these tools came to the fore.

6:35 In this decisive third clash with Darius III,

6:38 Alexander managed to turn the tables

6:40 of the battle through military improvisation.

6:43 During the battle, the Persians managed to pin

6:45 the Greeks' flanks with their cavalry and chariots,

6:48 partly lured by Alexander himself and his companions

6:51 on the right flank of the Hellenes.

6:54 However, Alexander managed to use his rear guard to charge from the right wing

6:58 of the centre formation and break into the Persian

7:01 centre at the back of the battlefield.

7:03 The chariots were unable to turn in time, too busy with the Greek flanks.

7:08 Eventually, Darius had to flee for fear of being surrounded and captured,

7:12 defeated by Alexander’s military skills.

7:15 Darius’s military forces were not incapable of fighting wars;

7:19 far from it, in fact.

7:21 The Achaemenid armies were always a cosmopolitan behemoth of the finest

7:25 of the thousand nations ruled by the Achaemenid empire.

7:29 However, the aforementioned political turmoil within

7:31 the rather labyrinthine structures of the Achaemenid

7:34 court meant that Darius was not as able to counter Alexander’s march.

7:39 For instance, Darius did indeed prepare for the Greek attack,

7:43 ordering the satraps of Asia Minor to fight off the Hellenes.

7:47 However, there were military issues on multiple fronts in the late 330s BCE,

7:53 including a revolt in Egypt.

7:55 Thus, Darius had to both prepare for Alexander’s coming,

7:58 but also tame the breadbasket of his empire.

8:01 Unfortunately for Darius,

8:02 by the time he managed to bring some stability to Egypt,

8:06 Alexander had established a foothold in Asia Minor

8:09 upon his victory in the Battle of Granicus.

8:12 The Persian military was also great in numbers,

8:14 but in the two battles in which Darius fought Alexander, Issus and Gaugamela,

8:19 it proved to be unable to adapt quickly to the tides of the battle.

8:24 Many explanations have been given for this weakness,

8:27 from bad leadership by Darius himself to the choice of battlefield

8:31 terrain at the Battle of Issus to inflexibility in battle tactics.

8:35 Whatever the case, Alexander’s military capacities were both

8:38 more robust and more adaptable than those of Darius.

8:42 Thus, when the two titans clashed,

8:45 Persian numbers could not overcome Greek phalanxes.

8:49 Logistical Factors: Alexander’s success,

8:50 at least in the first decisive half of the expedition across Persia’s realm,

8:54 also highly depended on logistical masterstrokes.

8:57 In our previous video on Alexander’s logistics,

9:01 we mentioned that Alexander’s troops carried a lighter

9:04 load than previous Greek forces and rarely used carts.

9:08 This flexibility of movement was important throughout Alexander’s campaigns,

9:12 but in Asia Minor and the Levant, he had one further logistical boon.

9:18 Alexander’s naval support followed him throughout

9:20 Asia Minor as well as the Levant,

9:22 through his important battles in Tyre and Gaza.

9:25 They provided him with logistical and provisional support as the general

9:30 solidified his control over the western parts of the Persian Empire.

9:34 In addition, Asia Minor’s populations included

9:37 Greeks who were friendly to Alexander

9:39 and gleefully gave him supplies for his early campaigns of the 330s.

9:44 Many Levantine and Cypriot cities also submitted and fed Alexander’s troops,

9:49 despite the famous resistance of the Tyrians.

9:52 And of course, the Egyptians who controlled

9:55 the great agricultural wealth of the Nile

9:58 River eagerly saw Alexander as a liberator

10:00 from the Persians they so often revolted against.

10:04 Alexander’s logistics strained on occasion in Asia Minor,

10:08 but only really became unsustainable when he chased

10:11 after the usurper and murderer of Darius, Bessus.

10:14 In Bactria, Sogdiana, Gandhara, and Arachosia,

10:17 where the terrain was far from Persepolis and rather harsh,

10:22 Alexander’s army did indeed struggle.

10:24 It was only when they found local support,

10:27 like when Gandharan kings allied with him,

10:30 that Alexander was spared complete oblivion.

10:32 Our sources on the logistics of Darius III are almost non-existent,

10:38 so we must speculate based on the Persian Empire’s issues at the time.

10:42 Darius does seem to have been able to sustain large armies on the march

10:46 and to have provisioned his forward operating hubs

10:49 in Asia Minor that were manned by local satraps.

10:51 We must also not forget that his forces were

10:54 multinational and could draw resources from across the empire.

10:57 It was thus not a question of how many provisions Darius could acquire,

11:01 but of where and how to utilise them.

11:04 The main disadvantage of his logistics may

11:07 have stemmed from the army's large size;

11:10 it was likely less flexible than Alexander’s forces.

11:13 Whereas the Greeks could cover long distances with some ease,

11:17 the Persians still had to maintain

11:19 their massive trains of supplies and equipment,

11:21 along with a larger number of servile populations

11:24 to fill support roles such as cooking and smithing.

11:27 In addition, the loss of control over Asia

11:30 Minor and Egypt cost the Achaemenid forces dearly,

11:33 for now their main supply lines had to come from farther in from Persia itself.

11:39 Thus, the local logistics of the Persians, who were meant to defend against

11:44 Alexander until Darius amassed his tremendous forces,

11:47 had to rely on often unstable and desertion-prone local collaborators.

11:51 The major defeats that Darius faced at Issus

11:55 and Gaugamela likely shattered his logistical network,

11:58 and when Alexander captured Persepolis, Darius lost most of the legitimacy

12:03 that had allowed him to muster many resources.

12:06 Propaganda Factors: Wars of conquest are often just

12:09 as much won by rhetoric as by arms, and here is where another convergence

12:13 of circumstances contributed to Alexander’s victory over Darius.

12:17 The Macedonian youth who entered Asia Minor after subduing rebels

12:22 in the Balkans had an ideological mission he preached wherever he went:

12:27 the liberation of the Greeks of Asia Minor from the Persian yoke

12:31 and vengeance for the Persian invasion of Hellas a century and a half prior.

12:36 Or at least, that is what he claimed to his Greek audiences.

12:40 In reality, Alexander was a masterful political propagandist,

12:45 keenly adapting his message to whoever he was addressing.

12:48 For the Greeks, he focused on his anti-Persian pedigree

12:51 and on the liberation of the Hellenes of Asia.

12:54 But when he went to the Levant and Egypt,

12:56 he behaved as both their liberator and a man

12:59 who wished to engage with the local cultures.

13:01 When he ended up taking the family of Darius hostage,

13:05 he is also said to have treated them with respect.

13:08 Over time, and to the dismay of many of his Companions,

13:11 he adopted certain local elements in clothing and ruling style.

13:15 For example, he tried to incorporate the Persian

13:18 customs of the Royal Tent and proskynesis,

13:20 or prostrating oneself before the King of Kings, into the way he was addressed.

13:26 As we discussed in our ‘Persianisation of Alexander’ video,

13:31 the Macedonian general hoped to build an ideology

13:35 of universal monarchy using both Greek and Persian elements,

13:39 a propaganda tactic which allowed him to assert

13:42 his control over most of the Persian Empire.

13:45 His propaganda tactics may have alienated some of his Companions at times,

13:49 but they gained him support and rapport

13:52 with local elites throughout the Persian Empire.

13:54 Alexander’s political theatre allowed him to assert control over

13:58 the lands he took by the sword and spear.

14:01 In the case of Darius, we have little surviving of his propaganda

14:05 efforts to rally the empire to his side.

14:07 Given that he was a distant relative of the Achaemenids,

14:11 his claim to the throne must have been weak at first.

14:14 And yet he managed to survive on the throne

14:17 for almost six years and amass a large army against Alexander,

14:21 only losing legitimacy when the latter defeated him decisively in battle.

14:25 Nor can we readily accept claims that Darius was weak

14:29 because of the presence of the eunuch Bagoas at court.

14:32 This is because our sources discussing the matter are

14:35 Greek and thus heavily biased in favour of Alexander.

14:38 What appears to have been the main issue of Darius’s own political

14:42 manoeuvring was that the Achaemenid Empire

14:45 was already strained from political turmoil.

14:47 For the Levantine and Egyptian audiences that received Alexander,

14:51 the propaganda of the King of Kings seemed

14:54 far less believable after decades of turmoil and revolts.

14:58 The only remaining audience that Darius could rely on, the Persian elites,

15:03 probably could not reconcile his claim to fame

15:06 and kingship when Alexander achieved his victory in Gaugamela.

15:09 The recent history of the Achaemenid Empire made Darius’s

15:13 political and rhetorical manoeuvring much more difficult than Alexander’s,

15:18 who was a new power whose ideology was

15:22 not yet tainted by decades of imperial overreach.

15:26 Administrative Factors: Finally,

15:27 there were administrative factors that enabled Alexander’s victory,

15:29 namely his ability to secure the confidence

15:32 of the elites he ultimately conquered.

15:35 This is not an innovation of the Greek general himself; it was,

15:39 in fact, a key ingredient in the recipe of success for the Achaemenid Empire.

15:44 Alexander’s success was in taking these tactics,

15:47 as well as other Achaemenid administrative institutions,

15:50 and using them to his advantage.

15:52 Thus, Alexander was not just relying on propaganda to conquer the Persians,

15:57 but building and adapting networks with local elites.

16:01 For instance, when he conquered Ionia upon his landing in Asia Minor,

16:05 he restored the democracies of the city-states

16:08 but ensured they paid vassalage taxes to him.

16:10 When he conquered the core of the Persian Empire in Persepolis and Susa,

16:15 he tried to engage with and maintain many satrapal administrative structures.

16:19 Alexander often innovated by placing Greeks

16:22 in positions of authority alongside some Persian satraps,

16:26 as well as by securing the allegiance of many Achaemenid nobles at court.

16:30 This is because the Achaemenid Empire’s political and administrative core was,

16:35 according to Rolf Strootman, a large web of social networks which

16:40 Alexander understood he needed to insert himself into.

16:44 This combination of continuity and innovation was

16:47 key in Alexander securing control over Persia.

16:51 Darius III appears not to have been able to have

16:54 an equal level of control over both imperial and local social networks.

16:58 His uneven control over the Achaemenid realm was a detriment

17:01 to his capability to block Alexander

17:04 from establishing a springboard in his territory.

17:07 This allowed the Macedonian to gain additional territories

17:10 through the effective use of logistical supply chains.

17:13 It was also much easier for social elites in Judaea, Egypt,

17:17 and parts of Asia Minor to change their allegiance to Alexander.

17:20 Darius, thus, only had the core of the Persian elite to side with him.

17:25 He was, however, not able to sustain this support

17:28 when he was defeated in battle by Alexander.

17:31 This weakness may have stemmed from the sheer magnitude of his defeats,

17:35 or from his provincial origins as a distant relative of the royal family.

17:39 Thus, Darius fled to the east, to the mountains of Bactria and Sogdiana.

17:43 But his alliance structure was insecure,

17:46 and the satrap-turned-pretender Bessus killed him.

17:49 The convergence of the previous military and propaganda factors,

17:52 as well as the instability of the Persian Empire's background,

17:56 made the administrative foundations of Darius’s

17:58 defence against the Greek invasion rather shaky.

18:01 Once they came under the slightest pressure,

18:04 Darius lost his legitimacy in the eyes of his fellow nobles.

18:08 Alexander’s swift capture of those institutions as soon

18:12 as Darius fled made any counter-attack highly implausible.

18:17 Conclusion: In the end, it was a combination of historical factors

18:20 that allowed for Alexander’s conquest of Persia.

18:23 Alexander’s genius was an important part of the equation,

18:27 but he also faced a formidable opponent in Darius III.

18:30 Thus, it was both Alexander’s ability

18:32 to easily establish a foothold in Asia Minor

18:35 and the issues rocking the Persian Empire

18:38 that gave him a solid foundation for victory.

18:41 In addition, Philip’s military reforms and Alexander’s own strategic

18:45 capabilities enabled a push into Persia and the Levant.

18:49 Alexander’s own diplomatic and administrative skills,

18:52 along with the use of Achaemenid and Levantine officials,

18:55 helped cement Greek rule,

18:57 and the stunning military victories at Gaugamela, Issus,

19:00 and Granicus ultimately cost Darius his power base.

19:04 Alexander's victory was not inevitable

19:06 and was partly due to favourable circumstances.

19:10 But it was also built on prudent

19:12 foundations and Alexander’s own ability to innovate,

19:15 as well as the reliability of his Companions.

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