1) In November 333 BC, Alexander the Great's army encountered the massive Persian army of Darius III near Issus in Cilicia. 2) Alexander redeployed his forces to concentrate his cavalry on his left wing against the large Persian cavalry. His decisive charge then broke through the Persian lines and threatened Darius himself. 3) With the Persian king fleeing and his army in disarray, Alexander won a decisive victory though he was unable to fully pursue the routed Persians before nightfall.

1. The Campaign and
Battle of Issus
333 B.C.
Dr. Johstono

2. TheCampaignsofAlexander,334-324B.C.
Alexander of Macedon invaded the region of Cilicia early in the 333 campaign season. He
probably crossed the Taurus range in May or June.

3. Alexander’s army crossed the Cilician gates in the Taurus mountain range, and camped at Tarsus
for more than a month after Alexander fell ill. In the meantime, he received intelligence that the
Persian Emperor, Darius, had departed Babylon with his Royal Army. Alexander received
reinforcements at the start of the campaign season, bringing his army to about 47,000 men,
according to the 2nd-century historian Polybius (Histories 12.19.3), but estimated closer to 30,000
men by Fuller and Delbrück.

4. TheOperationalContext
Alexander camped at Issus in eastern Cilicia, and had to decide whether to try to take the
northern Amanian Gate or the southern Assyrian Gate to get out of Cilicia and make contact with
Darius’ army. He had already defeated the Persian Satrapal armies in Asia Minor; defeating the
Royal Army in Syria might permit a rapid advance on Mesopotamia and end the war. But the two
passes were far apart, and he had poor intelligence on Darius’ movements.

5. Alexander moved south, but Darius had taken the northern route. Darius’ army cleared the
pass and got into Alexander’s rear about the same time Alexander had secured the
southern pass. Alexander had several options, but for several reasons he chose to turn his
army around and march north to meet Darius along the Cilician coast near Issus.
The resulting battle of Issus was the second of Alexander’s four great pitched battles in his
Asian campaign. The battle probably took place in November 333 B.C.

6. Sources
Up to this point, the ancient sources—Arrian, Diodorus of Sicily,
Plutarch, Justin, Curtius, and Polybius—are in basic agreement.
They agree that the battle was fought at the Pinarus river south
of Issus, too. But they disagree on several points:
1. The numbers and dispositions of troops
2. The actions of Alexander
3. The particular outcomes of the battle (although all agree it
was a victory for Alexander and the Macedonians)
The most important modern studies are those by Hans Delbrück
and J.F.C. Fuller. Although there are many accounts of the battle
that are more recent, all rely heavily on these earlier studies.

7. The Battlefield
• The Pinarus river flows east to west,
and ancient sources agree that
Darius posted his army along the
north bank. Delbrück and Davis
emphasize the difficulty in crossing
its steep banks.
• The coastal plain is narrow, but at the
Pinarus widens to a maximum of 2
miles before coming to the eastern
mountains.
• The Pinarus created a forward
obstacle, while the mountains and the
sea constrained both flanks.

8. The Persian Royal Army
• Polybius criticized Callisthenes, an eyewitness, for claiming there were 30,000
Persian cavalry and 30,000 Greek mercenaries holding the Persian right wing
because those numbers were obviously inflated and could not have fit on the
battlefield (Hist. 12.18.2). Other sources give similarly inflated numbers for the
Persian army: Arrian (2.8.8), usually the most reliable Alexander historian, gives
600,000. Delbrück suggested they may have been as few as 25,000, but most
treatments have followed Fuller in sticking to about 100,000.
• The sources are consistent in describing a strong cavalry contingent, a large
contingent of Greek mercenaries, the Persian Kardakes-- trained infantry armed
similarly to Greeks, who had been trained and armed to go toe-to-toe with the
Macedonians--and an unnumbered contingent of ranged troops.
• From other evidence it seems likely the Greeks were up to 10,000 strong, and
the Kardakes in most of the sources were twice the size of the Greeks, and the
cavalry the same number as the Greeks. If those ratios held true, it suggests
those major contingents numbered 40,000 in all, and the whole army, after
including ranged troops, perhaps 60,000.
• The important thing here is that Western tradition about Eastern armies
emphasized their sheer size and non-professionalism, which means they were
practically always exaggerated. But Darius’ army was a professional force, and as
a professional force needed to be smaller in order to manage command and
control.
• In conclusion, the armies were probably of similar size and professionalism, but
Alexander’s army was more experienced, and Darius’ slightly larger.

9. Persians and Macedonians
Persian Kardakes Hoplite Macedonian Pike Phalanx

10. Battle Dispositions
Alexander advanced toward the Pinarus and began deploying his men from column
Into line as he approached and could observe the Persian deployment. The battle took
place toward evening.

11. Battle Dispositions
• Alexander planned to put his main maneuver troops on his
right wing, but when he saw the Persian cavalry concentration
on the beach (their right), he redeployed the majority of his
cavalry to his left wing.
• Alexander saw that the Persians had posted missile troops
south of the Pinarus in two places: a few in the mountains to
harass his flank, many more in front of the Kardakes posted on
the left wing.
• He dispatched his best light infantry to chase off the men in the
mountains.
• He kept his lines out of missile range from the troops posted to
their front while moving his men into position in good order.

12. Alexander’s Attack
• Diodorus says he waited
until he spotted Darius,
then charged right at
him (17.33.5)
• Plutarch (33.2) says he
waited for an augur to
declare the gods’ favor
for the charge
• Arrian (2.10.3) says he
led his maneuver force
into missile range, then
charged “at the right
moment” to pass under
the arrow volleys

13. Battle Dispositions
Alexander’s rapid advance under missile fire caught the ranged troops in the middle
of redeploying through the Kardakes’ lines, and both units routed “on contact”
according to Arrian 2.10.4. All the sources generally agree that Alexander then led or
wheeled his elite troops to the left in an attempt to kill or capture Darius himself.

14. ALEXANDER’SDECISIVECHARGE
This Roman mosaic, copied after a contemporary Hellenistic painting, depicts Alexander (at
left) charging Darius (center) who is attempting to flee. The Macedonian pikes are visible in
the background, demonstrating that Alexander is attacking from the rear of the
disintegrated Persian left wing. Alexander is depicted striking down one of Darius’ kinsmen.

15. THEOTHERWING
Darius fled near nightfall, but Alexander could not pursue at first. His elite maneuver
elements pushed toward the Persian right wing, where the Greek mercenaries and Persian
cavalry, fighting from the banks of the Pinarus, were edging toward victory over the
Macedonian left. 120 Macedonians were killed in a single, hard-pressed regiment (Arrian
2.10.7), and only near-envelopment convinced the undefeated Persian right to withdraw.

16. Outcomes
• Darius flew from the field, and most of the army fled with
him. Ancient historians described very heavy casualties on the
Persian side, all agreeing on 110,000 killed and captured. But
they also state the pursuit only began at nightfall. Whatever
the losses, the Persian army outfitted for heavy infantry
combat was effectively destroyed. The Persian King of Kings
had been defeated in battle, but survived. The baggage train
of the Persian army was captured.
• 280-450 Macedonians were killed and more than 4500
wounded (Justin 11.9.10, Curtius 3.11.27).
• In the right wing, the Greek mercenaries and Persian cavalry
seem likely to have given as good as they got and withdrawn
with few losses (Fuller 162).

17. Sources
Primary
• Polybius, 12.17-23; Curtius, 3.8-11.15; Justin, 11.9.1-9;
Plutarch, Alexander, 20.1-5; Arrian, 2.8-11; Diodorus, 17.33-
35.
Secondary
• Fuller, JFC. 2004 (reprint from 1960). The Generalship of
Alexander the Great. De Capo Press: 154-162.
• Delbrück, Hans. 1990 (reprint from 1920). Warfare in
Antiquity. University of Nebraska Press: 196-206.
• Davis, Paul. 2013. Masters of the Battlefield. Oxford University
Press: 30-35.