Battle of Issus The Battle of Issus occurred in southern Anatolia , in November 333 BC . The invading Macedonian troops , led by Alexander the Great , defeated an army led by Darius III of Achaemenid Persia in the second great battle of Alexander ' s conquest of Asia . After the Macedonians soundly defeated the Persian satraps of Asia Minor ( led by the Greek mercenary , Memnon of Rhodes ) at the Battle of the Granicus , Darius took personal command of his army . He gathered reinforcements and led his men in a surprise march behind the Macedonian advance to cut their line of supply . This forced Alexander to countermarch , setting the stage for the battle near the mouth of the Pinarus River and the town of Issus . Location . The battle took place south of the ancient town Issus , which is close to present - day Turkish town of Iskenderun ( the Turkish equivalent of " Alexandria " , founded by Alexander to commemorate his victory ) , on either side of a small river called Pinarus . At that location the distance from the gulf of Issus to the surrounding mountains is only , a place where Darius could not take advantage of his superiority in numbers . Speculation on the location of the Pinarus has taken place for over 80 years . Older historians believed it to be the Deli Tchai river , but historians N . G . L . Hammond and A . M . Devine have made convincing claims that the Pinarus is actually the Payas River , the latter using eye - witness examination of the river , which may not have drastically changed since antiquity . Their evidence is based on Callisthenes ' accounts of the measurements of the battlefield and distances marched by both side ' s armies in the prelude to the battle and distance given by Diodorus after the battle . Background . Alexander set out into Asia in 334 BC and defeated the local Persian satraps at the Battle of the Granicus . He then proceeded to occupy all of Asia Minor , with the idea of capturing all coastal settlements so as to negate the power of the vastly superior Persian fleet . He captured several important settlements such as Miletus in 334 BC and Halicarnassus , a siege lasting four months , starting in late December the same year . While Alexander was in Tarsus he heard of Darius massing a great army in Babylon . If Darius were to reach the Gulf of Issus he could use the support from the Persian fleet under Pharnabazus still operating in the Mediterranean Sea , thus easing his supply and possibly landing troops behind the enemy . Alexander kept his main army at Tarsus but sent Parmenion ahead to occupy the coast around Issus . In November , Alexander received reports that the great Persian army had advanced into Syria , to a town named Sochi . Alexander decided to mass his scattered army and advance south from Issus through the Pass of Jonah . Darius knew that Parmenion held the Pass of Jonah and thus chose a northern route of advance . The Persians captured Issus without opposition , and cut off the hands of all the sick and wounded that Alexander had left behind . Now Darius found out he had placed his army behind the Macedonians and had cut their supply lines . He then advanced to the south and got no further than the river Pinarus before his scouts spotted Alexander marching north . Darius had to set up camp on this narrow coastal plain . Motives . There is much debate as to the motives of Alexander and Darius preceding Issus . A strong and convincing modern perspective , based on Curtius , is that Darius was forced to move camp to terrain that favored Alexander because Alexander was fighting defensively due to a recommendation by his war council and Parmenion . Darius ' large army could not be supported in the field during winter and his cities in Phoenicia were already in unrest at the arrival of Alexander . Darius was forced to move his large army to a small battlefield , greatly to the advantage of Alexander ' s smaller force . Alexander was waiting for Darius to come south around the Amanus Mountain range because the pass Darius would have used , the Belen Pass , was much closer to Sochi and offered the quickest access to the area Alexander defended . Alexander was waiting to the west of the Belen Pass at Myriandrus to spring a trap on Darius as he crossed through the Belen Pass or through the Pillar of Jonah if he moved north , where Darius ' army would be disorganized and disjointed in the narrow crossing . Darius instead moved north from Sochi and around the mountains , emerging behind Alexander ' s position and on his supply and communication lines . Thus Alexander was forced to march to Darius , who had caught him off guard in a large flanking maneuver . This gives the illusion that Darius was the one acting defensively , since Alexander was forced to march to him . Combatants . Persian army . Some ancient sources ( Arrian and Plutarch ) , who based their accounts on earlier Greek sources , estimated 600 , 000 Persian soldiers in total , while Diodorus and Justin estimated 400 , 000 , and Curtius Rufus estimated 250 , 000 . Modern historians find Arrian ' s count of six hundred thousand men highly unlikely . They argue that the logistics of fielding more than 100 , 000 soldiers in battle was extremely difficult at the time . Hans Delbrück gives an estimate as small as 25 , 000 , although most ( including Engels and Green ) estimate the total size of Darius ' army to be no larger than 100 , 000 at Issus , including 11 , 000 cavalry , 10 , 000 Persian Immortals , and 10 , 000 Greek mercenaries . Warry estimates 108 , 000 in total . Macedonian army . The size of the Macedonian army may not have exceeded 40 , 000 men , including their other allies , led by Alexander . Alexander ' s army may have consisted of about 22 , 000 phalangite s and hoplite s , 13 , 000 peltast s , and 5 , 850 cavalry . Battle . The Macedonians advanced through the Pillar of Jonah . Alexander led his Companion cavalry on the right flank and he set his Thessalian allied cavalry on the left of the phalanx with Parmenion in command . Darius formed his line with his heavy cavalry concentrated next to the coast on his right , followed by the Greek mercenary phalanx ( historian A . M Devine places them at a strength of 12 , 000 , comparable to the Macedonian phalanx ) . Next to the Greek phalanx Darius spread his Persian infantry , the Cardaces , along the river and into the foothills , where they wrapped around to the other bank and threatened Alexander ' s right flank ( the formation resembled " gamma " , Γ ) . Arrian gives an inflated figure of 20 , 000 to these troops . Darius positioned himself in the centre with his best infantry , the Greek mercenaries , and his royal cavalry guard . According to some historians , like P . Stratikis , he was trying to replicate the Hellenic battle formation of the Battle of the Granicus . The Persian cavalry first charged Parmenion and the allied cavalry , crossing the river to open battle . Alexander ' s left wing once again became the crux of the battle , as at Gaugamela two years later , where Parmenion held the wing long enough against superior Persian numbers for Alexander to make his calculated cavalry strike against Darius and break the Persian army . The Hypaspists led by Alexander , on foot , delivered an assault during this time across the riverbed on the Cardaces and managed to punch a hole through the Persian line . Alexander then mounted a horse at the head of his Companion cavalry and led a direct assault against Darius who fled from the battlefield . Alexander then saw his left flank and center in trouble , let Darius flee , and crashed into the rear of the Greek mercenaries . The Greek mercenaries broke up . The Persians saw that their Great King had gone and that the battle was being lost , and they abandoned their positions and fled in full rout . The Macedonian cavalry pursued the fleeing Persians for as long as there was light . As with most ancient battles , significant carnage occurred after the battle as pursuing Macedonians slaughtered their crowded , disorganized foe . Arrian notes Ptolemy I mentions that , while pursuing Darius , Alexander and his bodyguards came upon a gap which they easily crossed on the bodies of dead Persians . It was a decisive victory for Alexander . Aftermath . The Battle of Issus was a decisive Macedonian victory and it marked the beginning of the end of Persian power . It was the first time the Persian army had been defeated with the King ( Darius III at the time ) present . After the battle , the Macedonians captured Darius ' wife , Stateira I , his daughters , Stateira II and Drypetis , and his mother , Sisygambis ; all of whom had accompanied Darius on his campaign . Alexander , who later married Stateira II , treated the captured women with great respect .