Alexander marched his army over 250 miles over the mountains from Pelium to the outskirts of Thebes in less than two weeks. With his army in place, he then waited "in order to give the Thebans time to think things over, in case they should change their minds and decide to treat with him." (Arrian, The Conquests of Alexander, 7). Instead, the Thebans sent a force of light infantry, cavalry and missile fire to attack the Macedonian outposts. Alexander moved his army near the Theban gates and again waited for the Thebans to back down. Inside the city, many wished to do so - but the hard core insisted on war. Finally, the battle was joined when (according to Ptolemy's account), Alexander's general, Pediccas, began an assault on his own initiative, which Alexander then supported. When Perdiccas' men began to falter against the Theban opposition, Alexander put the full force of his infantry and archers behind his troops. The gates of Thebes were breached and, after long and hard fighting, the Theban troops were beaten and the surviving cavalry and infantry fled. The allied Greek soldiers in Alexander's army - many of whom had suffered under Thebes' harsh military hand in the past - plundered the town. Alexander gave strict orders to spare many in the town, and to prevent the sack from becoming total - it is on record that he saved the house of the poet, Pindar, from destruction. After the town fell, Alexander consulted with his allies, consistent with his role as hegemon, and it was agreed to raze Thebes to the ground as an example.

This action has reaped as much odium as anything Alexander did. There are, however, reasons behind his action in Thebes, and it was not only to frighten the rest of the city-states before he took his armies east to Persia.

In ancient warfare, it was standard procedure (a practice followed by many city states in the past, including Thebes) to devastate any town or people on the losing side of war. All the young men would normally be killed who had not already fled; the non-combatants would, to a man, woman, or child, normally be sold into slavery. Thebes had also earned many enemies for its actions in recent decades: it was not some bastion of liberty, but a city that had reneged on its promises through the Corinthian league and had been a brutal aggressor against other Greeks in the long civil wars. Perhaps knowing the blow to his reputation the destruction of Thebes would cause, Alexander gave the Thebans every opportunity to negotiate, which they refused.

Alexander's reputation deserves some of the opprobrium of the destruction - but not the reputation as a crazed sacker of cities which later historians tried to foster. Thebes had on several prior occasions reversed its treaty positions; in the aftermath of the Battle of Chaeronea, it had agreed to maintain the peace and it had signed to the League of Corinth and its provisions that the city-states would not break the peace among themselves. It had refused to negotiate. And it paid the price.

The destruction of Thebes was a sensation throughout Greece. Nothing Alexander could have done would have more firmly frightened and dissuaded the other city-states from attacking him. Immediately, ambassadors set out hotfoot for Alexander's camp to beg forgiveness if they had aided Thebes, or to compliment him for its destruction (the Athenians fell into the latter camp). Athens had done everything except come out openly as an ally of Thebes, and Demosthenes himself boasted that Alexander was either dead in his northern battles or would do nothing; with a swift change of tune, the Athenian delegation welcomed Alexander safely home from Illyria and "thoroughly approved of his punishment of the Thebans for their revolt." (Arrian, 10) Alexander countered, sternly, demanding that the anti-Macedonian party in Athens be surrendered to him (including Demosthenes), as he held them responsible for the continual friction between the two states. But when the Athenians begged him to relent, he did so, only asking that one Athenian named Charidemus be exiled - which was promptly done.

In his treatment of Thebes, Alexander revealed several traits consistent with his later actions in Persia. He operated carefully under the authority granted him by the League of Corinth. He moved swiftly to confront the Thebans, but then attempted to negotiate before battle (the long wait outside the gates of Thebes is confirmed by Diodorus Siculus). Once action was inevitable, he struck hard and without mercy. As with Athens, he negotiated fiercely but was willing to be flexible, as he did by permitting his Athenian enemies to remain peacefully in Athens. He had made Thebes and example and the example went some way to guard the peace in Greece in the months and years ahead, when he would be far from Greece. Most importantly, he had made it clear that the agreements of the League of Corinth would be upheld and that the internecine warfare between the city-states of Greece, almost continual for decades, would not be tolerated under his leadership.