In September 331 BCE, Alexander marches east, into the Persian Empire’s hinterland. He heard scouting reports that Persian King Darius had assembled another great army and was prepared for a decisive battle with the Macedonians. Both armies ultimately met on a huge open field near Gaugamela, in a decisive conflict of two of ancient antiquity’s greatest empires.

It is 331 BCE. After conquering Tyre and Gaza, the Macedonian army rested in the fertile Nile Valley. Since Egypt was not the most loyal of Persian provinces, the Egyptian satrap did not confront Alexander. Post-Issus, Persian King Darius sought to thwart Alexander’s amazing victory via diplomacy. Even still, the Macedonian King declined Darius’ generous offer three times, and began planning the forthcoming Babylonian war. After completing all preparations, the Macedonian troops marched back to Phoenicia in early April. Notably, Alexander devoted close attention to logistics operations during his battlefield preparations. Keeping such a large army in top form for years away from home needed meticulous planning and supervision.

The Macedonian army stayed close to the shore, relying on the ship for supplies. By the time Alexander crossed the Euphrates, the new Persian army was being organized. The King of Kings anticipated the Macedonians to march up the river to Babylon; therefore, he ordered the looting of the Euphrates valley. However, the riverside towns were well-defended, making supply collecting difficult, so Alexander selected a northern path with more rural communities and easier access to food and water. Darius immediately left Babylon, travelling north along the Tigris River’s east bank.

A large mounted army under Mazaeus, Babylon’s ruler, was sent to protect the northern Tigris bridges and loot its east bank. Mazaeus failed to confront the Greeks throughout the passage, and Alexander reached the east bank in mid-September. Darius was getting near to the combat, so he began looking for a good location. He made his camp on a vast plain near Gaugamela and prepared. Meanwhile, Alexander’s men captured a Persian scouting expedition and discovered Darius’ camp 30 km to the east. In a flash, the Macedonian King sent his own scouts and moved on the enemy after a few days of respite, Alexander headed forth towards the Persian fortifications. In the face of the complete Macedonian army, Mazaeus’ unit withdrew without a struggle and rode back to the camp, surrendering the hill. Although the hill was useful, Darius still dominated the broad fields, which suited his bigger force better. Therefore, the hill was essential but lost.

Alexander took the hill and decided to make a camp there after a quick survey. The higher terrain afforded him a clear view of the Persian camp and military placement. Alexander did not have to hurry since the hill was ideally adapted for defense, so he prepared his forces properly nourished, rested, and mentally prepared. Due to Mazaeus’ failure, Darius’ men were concerned about likely Greek attacks during the night. Darius possessed better troops, cavalry, and terrain, but he had to wait for the Macedonians to act first, since assaulting the crest was out of the question. As the sun fell, Alexander and his officers reviewed the forthcoming conflict. His deputy, Parmenion, suggested a nocturnal assault to catch the Persians off guard, but Alexander rejected the notion as too hazardous.

The Macedonian leadership decided to assault the next morning. After a long night, the sun rose and lighted the battlefield. It was October 1st. The Persian army had been waiting all night for the Macedonian invasion, which never arrived. Darius exploited his huge empire’s workforce effectively, gathering up to 100,000 warriors to battle for him. The Persian center consisted of ten thousand Immortal troops and a few thousand Greek mercenaries. However, Darius’ army’s true might was on the flanks. The danger of 30,000 superb cavalrymen from multiple Persian satrapies was significant on a vast and level battlefield. Notably absent from the fight were Darius’ Indian scythed charioteers and his fifteen elephants. The remainder of his army was made up of infantry battalions from Achaemenid tribes, whose combat prowess was dubious. Due of the magnitude of the Persian army, Darius had his trusty generals Mazaeus and Bessus command. Historians debate the precise placements of Bactrian cavalry and Parthian infantry in the Persian battle line.

When Alexander and his men woke up, the re-energized Macedonian army left the hill and started their deployment. The battle line was tilted, with the right flank facing the Persian center. To prevent encirclement, both flanks were fortified and curled rearward. On the Macedonian front, an orderly sarissaphalanx backed by robust hypaspist troops. Thessalian infantry were on the left flank, Companion cavalry on the right. In the Second line, Thracian and Illirian troops, Alexander and Parmenion shared leadership like in past conflicts. Darius countered the

Macedonian king’s maneuver by widening his left flank and matching his movement. Darius had leveled and cleansed the battlefield for better chariot usage, which is why he desired the Macedonians to stay on the prepared terrain. Persian cavalry assaulted Alexander’s right flank. The battle raged on, with no winner. Eventually, Macedonian cavalry overcame the Persian forces and defeated them, albeit severely damaged. To his left, Darius deployed a scythed army to invade the Greek capital. However, defenders opened their lines, allowing attackers to ride through the line while showering javelins on them.

This forced Parmenion to surrender ground as many Greeks died and the Persian right flank headed by Mazaeus continued their attack. Parmenion was outnumbered and half encircled, but it was not the first time he had had to battle against the odds. His flank fought courageously and withstood the Persian attack. Alexander had moved his flank to the right, leaving a gap in the Macedonian center, Darius saw. The Persian monarch sensed an opportunity and dispatched his Immortal soldiers to seize it. However, that was bait. This revealed Darius’s core. Alexander seized the moment, moving Companion cavalry and flank forces to strike the Persian center, directly where Darius’ vulnerable royal guard stood. Despite second line reinforcement, the Macedonian assault rapidly breached the Persian line. Darius, like two years before, sensed the danger and left the battlefield. Alexander galloped back to relieve Parmenion’s flank. When the Macedonian left was ultimately rescued, the remaining Persian soldiers were quickly overpowered and defeated. Although Darius escaped again, delaying Alexander’s political aspirations to make himself King of Persia, the Achaemenid Empire’s military force was damaged. Macedonians enjoyed easy access to Mesopotamia and Persia’s capitals. By subjugating the Persian Empire, Alexander virtually ended its control in less than five years, but his thirst for power was not satisfied, and his story is still to be told.