Why Was Alexander the Great’s Victory at the Battle of Issus so Significant?

Tristan Hughes

4 mins

10 Dec 2018

On 5 November 333 BC Alexander the Great had his first encounter with Darius III, ‘The Great King’ of Persia at the Battle of Issus. His ensuing victory ensured that this was one of the key moments during his Persian campaign.

The road to Issus

Following Alexander’s victory at the Granicus and his subsequent capture of western Asia Minor, Darius, the Persian King, realised he could no longer devolve responsibility for defeating the Macedonian king to his satraps (barons). He thus gathered a great army and marched from Babylon to confront Alexander.

Meanwhile Alexander continued east, subduing the interior of Asia Minor. At Gordium he was confronted with the famous Gordion Knot which legend had it only the man destined to be king of Asia could untie.

In emphatic style Alexander took out his sword and slashed the knot in two, claiming it did not matter how the knot was untied, just that it was.

A painting by Jean-Simon Berthélemy showing Alexander the Great cutting the Gordion Knot with his sword.

After this morale-boosting act Alexander continued east and reached Tarsus in Cilicia, where he fell seriously ill after bathing in the local river. The illness was so severe that Alexander and his army were forced to remain there for months.

In the meantime, further to the east Darius and his army were awaiting Alexander’s arrival at Sochoi, a large plain in the province of Assyria that was well-suited for his large army. Yet because of Alexander’s illness, for weeks he and his army remained idle awaiting a battle they believed was imminent.

Darius grows impatient

Although his advisers strongly suggested he stay where he was and assured him that Alexander would eventually arrive, Darius soon grew impatient; he started to believe his foe was too frightened to face his large army on the battlefield. He therefore gathered his troops and led a surprise march through an unguarded pass into Cilicia.

In the meantime, Alexander had recovered and was marching down the coastline of the eastern Mediterranean in search of Darius’ army was, leaving his wounded men at Issus, a small coastal town in Cilicia, to recover.

Yet Alexander then received word that Darius was not in front of him. Instead he discovered that Darius and his army had emerged behind his lines at Issus, where they had slaughtered his wounded troops. Alexander had been caught 0ff-guard and at full speed he turned round to confront the Persian King.

A few days later their forces clashed at the Pinarus River, south of Issus.

A map of the movements of Alexander (blue) and Darius (red) prior to the Battle of Issus. Darius had caught Alexander off-guard, emerging behind his army and camping at the Pinarus River.

Why the battlefield’s topography worked in Alexander’s favour

Although the battlefield was Darius’ choosing, it lacked enough open space for his army to deploy effectively. The ancient historian Arrian claims Darius’ force numbered some 600,000 men. Yet this is evidently a gross exaggeration and modern estimates suggest the Persian army numbered somewhere between 60,000 and 100,000 men.

Alexander’s 40,000-strong army was thus heavily outnumbered. Yet the narrow length of the battlefield played to his advantage, proving just wide enough for him to deploy his Macedonian phalanx effectively.

This map hammers home the narrowness of the battlefield. Darius’ compact army is visible on the left of the river, contrasted with Alexander’s neatly extended line on the right.

The Battle of Issus

Having contained a small Persian force in the foothills to the right of his army, Alexander attacked. He realised that Darius’ left wing consisted of a mass of inexperienced Persian soldiers – archers and spear-wielding infantrymen mainly – and Alexander saw that this was the weak point in Darius’ defence.

The Persian centre, contrarily, consisted of veteran mercenary Greek infantry and his right, the finest cavalry force in Asia.

Alexander led his Companions across the river at full speed against Darius’ left flank, hoping to surprise those arrayed against them. It worked. Terrified by the speed of Alexander’s advance, the Persian volley of arrows proved dreadfully inaccurate and Alexander and his men reached the far bank of the Pinarus virtually unscathed.

Seeing Alexander and his cavalry emerging on their side of the river, the Persians lost their nerve and ran. Darius’ left flank crumbled.

Alexander and his cavalry duly enveloped the rest of the Persian line, surrounding the expert Greek infantry who up to that point had been proving more than a match for Alexander’s Macedonian phalanx in the centre.

Seeing the collapse Darius fled the field, many of his men following close behind.

The critical role of the Thessalians

Meanwhile on the left, Alexander’s Thessalian cavalry, who were renowned as the best cavalrymen in Greece, heroically fended off the Persian horsemen that had charged across the river. If they had not managed this, then the Persian cavalry would likely have surrounded and annihilated Alexander’s army.

Darius soon called on the aid of Scythian warriors to help him defend against Alexander the Great following his defeat at Issus. Learn more about these ferocious nomads in this interview with Dan Snow at the British Museum on HistoryHit.TV. Watch Now

Alexander recognised the critical role his Thessalians had played in victory, giving them the lion share of the spoils in Darius’ abandoned baggage train – a well-earned reward.

Among the spoils of Darius’ baggage train were the Persian King’s mother, wife and children whom Alexander was sure to treat with kindness and compassion.

Issus was only the beginning

After his stunning victory at Issus, Alexander took Syria and subdued the city of Tyre after a lengthy siege. He then marched to Egypt in 332 BC and founded the famous city of Alexandria.

A year later in 331 BC Darius would confront Alexander on the battlefield once more, this time gathering an even larger army and choosing a battlefield where everything looked in his favour. It would prove the decisive clash of Alexander’s Persian campaign and remains to this day one of the most iconic battles in history: the Battle of Gaugamela.