Alexander the Great had three major battles against the Persian Empire, those three battles were the battle of Granicus, the battle of Issus, and lastly the battle of Gaugamela. These decisive victories forced the Persian troops to retreat and given more time for Alexander to advance further into Persian territory.
“Battle granicus” by Frank Martini. Cartographer, Department of History, United States Military Academy – The Department of History, United States Military Academy . Licensed under CC BY-SA 3.0 via Wikimedia Commons – https://commons.wikimedia.org/wiki/File:Battle_granicus.png#/media/File:Battle_granicus.png
The Battle of Granicus was the first major battle between the two powers. It took place on the river banks of the river Granicus in 334 BC. The army of Alexander consisted of 40,000 men and it was augmented by some troops already located in Asia. There are inconsistencies on the Persian army, Arrian claims 20,000 cavalry and 20,000 Greek mercenaries but in fact there was 4,000 – 5,000 Greek mercenaries. The Persians made a mistake of locating their cavalry on the river banks causing the cavalry to be a stationary unit as their infantry was located behind them (Diodorus, Book XVII, 19). Alexander exploited the Persian mistake and decided to attack on the same day he arrived. He countered the cavalry by using the Pezhetairoi (six battalions that consisted of 9000 infantry) at the center, 3,000 hypaspists on the right, with cavalry on the right flank, this is where Alexander was located (Arr 1.16.45 – 50). On the left wing were the Thessalian cavalry and some allied forces. Alexander began his attack by attacking the Persian left flank and drawing the center and weakening it. Given the opening he sought, Alexander ordered a direct attack of his companion on the right flank, followed by his entire army. Once the Persian cavalry retreated, as Alexander’s forces proved too much for the Persians, leaving the Greek mercenaries open for an attack. The Greek mercenaries of the Persians surrendered but Alexander refused to negotiate and proceeded to slaughter them to make an example of traitors. Of the 5,000 Greek mercenaries, 2,000 were left and were sent to hard labor camps in Macedonia.
After his victory in Granicus, Alexander proceeded in occupying Asia Minor. Alexander sought to capture coastal settlements to reduce the power of the Persian Navy, as it was vastly superior to Alexander’s navy. Alexander captured Issus and kept marching south as he heard, Darius III, king of the Persian Empire, was located at Sochi. Darius marched north and went after Issus and recapturing before following Alexander’s trail south. Darius march south was interrupted, near the Pinarus River which had narrow coastal plain, when scouts spotted Alexander’s army marching north (Arr 2.6.2).
“Battle issus decisive” by Frank Martini. Cartographer, Department of History, United States Military Academy – The Department of History, United States Military Academy . Licensed under Public Domain via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Battle_issus_decisive.png#/media/File:Battle_issus_decisive.png
Darius set his troops as best he could with the limitations the rough terrain provided, on the flat terrain he placed his infantry and barbarians on both sides, and on the right flank he placed his cavalry. Alexander placed his pezhetairoi, carrying 18 foot long sarissas (Markle 1977), on the center; the Thessalian cavalry on the left, and the companion cavalry and Alexander were on the right. The battle plan was similar to the battle of Granicus, where the center infantry held the Persian infantry with the support of the left flank Cavalry as Alexander’s right flank cavalry overpowered the Persian left flank composed of barbarians. Due to the rough terrain the Macedonian infantry could not keep with the right cavalry creating an opening for the Greek Persian mercenaries to deal heavy damage (Arr. 2.10.7). Once The Macedonian cavalry had broken through the Persian left flank it went to support the infantry, causing Darius to flee the battlefield, causing instability on the remaining troops and they fled from the battlefield as well. This event marked a large victory on the Macedonian side, as no one had defeated the mighty Persian army with the king present.
“Battle of Gaugamela, 331 BC – Opening movements”. Licensed under Public Domain via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Battle_of_Gaugamela,_331_BC_-_Opening_movements.png#/media/File:Battle_of_Gaugamela,_331_BC_-_Opening_movements.png
The final clash between Alexander’s forces and Darius’ forces was at Gaugamela in the summer of 331 BC, but this time the Persian army was at its greatest, as they had an open flat battlefield, as they had leveled it and cleared it (Curt. 4.13.36– 7), and larger numbers (Arr. 3.13.5– 6; Diod. 17.58.2– 5 and Curt. 4.15.14– 17). Alexander’s formation was similar to the formation used at Issus. The Macedonian cavalry in both flanks were tilted inward in anticipation of the Persian flanking maneuver, leading the Persian cavalry away from the heavy infantry center. Darius focused on the Macedonian right flank by sending his front forces there and creating a thinning on his lines to the left of Darius. Alexander was quick to take advantage of the situation, taking the companion Cavalry directly towards the weak spot. The Macedonian pezhetairoi clashed with the Persian infantry, while Alexander cut through the weak spot. Instead of counterattacking, Darius’ forces rode towards the Macedonian camp( Cf. Burn 1973: 118) , who were then slaughtered by the reserve troops in the back of the army. Darius, once again had to flee the battlefield, as his center forces collapsed and prevented himself from being captured.
Alexander’s final battle opened the entirety of Persia to him. Persian morale was broken after three incredible defeats and Alexander took no time in allowing it to recover. He was able to pacify the rest of Persia and move on to the exotic lands of the northwestern Indus valley.
Quintus Curtius Rufus. Historiae Alexandri Magni
Quintus Curtius Rufus (1880). Vogel, Theodor, ed. Histories of Alexander the Great. London
Heckel, Waldemar (2012-03-29). The Conquests of Alexander the Great (Canto Classics). Cambridge University Press. Kindle Edition.
M. Markle, III, Minor (Summer 1977). “The Macedonian Sarrissa, Spear and Related Armor”. American Journal of Archeology (Archeological Institute of America) 81 (3): 323–339.