12,000 heavy infantry8,000 light infantry3,000 cavalry The Balkan campaign of Alexander the Great took place in 335 BC, against a number of rebellious vassals of the Macedonian kingdom.

[1] News of Philip's death roused many states into revolt including Thebes, Athens, Thessaly and the Thracian tribes to the north of Macedon.

[3] Before crossing to Asia, Alexander wanted to safeguard his northern borders and, in the spring of 335 BC, he advanced into Thrace to deal with the revolt, which was led by the Illyrians and Triballi.

Alexander ordered his heavy infantry to march in loose formation and, when the carts were thrown, either to open the ranks or lie flat on the ground with their shields over them.

[4] Descending on the lands of the Triballians Alexander found out that their king, Syrmus, had gathered his population near the River Lyginus.

[7][8] It was critical for Alexander to take this pass as it provided easy access to Illyria and Macedonia, which was urgently needed in order to quell the unrest in Greece at this time in Athens and Thebes.

Taking this place allowed Alexander to march his army to southern Greece quickly, which would eventually result in the total destruction of Thebes.

The Thebans refused to submit on merciful terms, and he assaulted the city, razed it to the ground, and sold all the survivors into slavery.