Darius's Empire

Persia had been the dominant power in the eastern Mediterranean since 547bc (when Cyrus the Great conquered the kingdom of Lydia in Asia Minor). Darius I invaded Greece in 490bc, and his successor Xerxes I had tried again in 480bc.

Although the Greeks survived these attacks, they never forgave the Persians. When Alexander invaded Persia in 334bc., he mentioned the way Persia interfered in Greek affairs and ‘disturbed the peace’ in Greece. Later, he accused Darius of murdering his father. But the official reason for the invasion, stated by the League of Corinth, was to avenge Xerxes’s invasion in 480bc.

Even after the defeat of Xerxes, however, internal feuds between the Greek city-states had allowed Persia to dominate Greece – for a time, the Balkan states (including Macedon) to the north of Greece were under Persian control, and the King’s Peace (387bc) returned the Ionian cities to the Persian Empire. Persia continued to interfere in Greek affairs, attempting, for example, to bribe Athens to rebel against Alexander in 336-5bc and maybe even organising Philip II’s assassination.

The Greeks, consequently, hated and feared the Persians. They looked back to the times of mythology when heroes such as Odysseus and Achilles had invaded and conquered Troy. Greek writers urged their leaders to attack Persia, saying that it was a weak empire which would be easily conquered. And, when he wanted to secure his hegemony over the Greek city-states in 337bc, Philip proposed … an invasion of Persia – he knew that nothing would unite the Greeks under him like a joint campaign against the old enemy.

Weaknesses of the Persian Empire

1.  Lack of Unity

It was not a unified empire (communications in those days did not allow so huge a country). Rather, it was a collection of semi-independent ‘satrapies’, which owed allegiance to the Emperor and paid taxes to him … but were governed by local rulers with the power to make decisions on the spot (which helped Alexander at the Battle of the Granicus). Some of these satrapies hated being part of the empire (e.g. Egypt welcomed Alexander as their liberator from the Persian Empire), and all of them were inclined to rebel when the Emperor was weak or in difficulty.
Thus the Persian Empire was arguably a house of cards, which LOOKED impressive, but collapsed when given a hard knock. .

2.  A government in chaos
At the time of Darius III, the government of the Empire was in chaos.
The strong ruler Artaxerxes III had died in 338bc (perhaps poisoned by his powerful eunuch Bagoas). Bagoes then killed all Artaxerxes’s sons but one, whom he put on the throne as Artaxerses IV. But Artaxerxes IV faced rebellions in Egypt and Babylon, and was killed, in his turn, by Bagoas in 336bc.
Bagoas then selected Darius III, a distant relative of the royal family, and put him on the throne – whereupon Darius seized power by killing Bagoas. But, at the Persian Court, Darius was still an ‘outsider’ and, two years later, the Persian government was still sorting itself out.

3.  A Weak Ruler

Darius was personally brave, and a decent general, but (as the Wikipedia author says) he was ‘a ruler of entirely average stamp’, with no experience of ruling an empire … faced by Alexander, a general and leader of genius.

4.  The Roads to Victory

In a bid to strengthen their rule by improving communications, the Persian rulers had built a good system of roads – notably Darius I’s ‘Royal Road’, which stretched from Sardis in Asia Minor to Susa in Persia. But these roads also opened the empire up to easy conquest – Lane Fox states that Alexander didn’t conquer the Persian Empire, he merely conquered its roads.

5.  A Second-Rate Army

Where Alexander’s Macedonian Army was a highly-trained, professional standing army, Darius’s army – apart from his core infantry (The Immortals) – was a conscript army of farmers and levies from the satrapies.
In particular, the Persian army lacked archers and slingers, so it could not engage at a distance.

Strengths of the Persian Empire

1.  A Great Civilisation
The Greeks called the Persians ‘barbarians’ but – compared to the warring Greeks, it was the Persians who were civilised. They had elegant court etiquettes, and gardens so beautiful that their name (paradeisoi) has come into our language as the word for heaven. They had an advanced religion (Zoroastrianism) which believed in one God, taught people to be kind and do good, and believed in a Saviour who would come in the end-times to renew the world. They had beautiful carpets, paintings and jewellery. Aristotle wrote that luxury had weakened the Persians, and led to their defeat – certainly one Persian diplomat brought his own bed-makers with him when he visited Greece.

2.  Huge Wealth
To invade Persia, Alexander borrowed 800 talents. Darius received an annual income of 10,000 talents from his taxes, and had a royal treasure-store of more than 200,000 talents.

3.  A Huge Army
*  Alexander invaded Persia with 50,000 men; Darius could turn out an army of 120,000.
*  Alexander had 6,000 cavalry, Darius had 30,000.
*  Darius's 10,000 ‘Immortals’ were among the best infantry soldiers in the world, and he could put into the field hundreds of terrifying, scythe-wheeled chariots.
*  He also had 50,000 Greek mercenaries (many of the enemies of Alexander who had fled to Persia to escape execution in Greece) … led by the exiled Athenian general Charidemus!