The Balkan campaign of Alexander the Great took place in 335 BC, against a number of rebellious vassals of the Macedon

Macedon

Macedonia or Macedon was an ancient kingdom, centered in the northeastern part of the Greek peninsula, bordered by Epirus to the west, Paeonia to the north, the region of Thrace to the east and Thessaly to the south....

ian kingdom. Alexander successfully pacified each in turn, leaving him free to begin the long planned invasion of Persia.

Background

In 336 BC, while attending the wedding of his daughter by Olympias

Olympias

Olympias was a Greek princess of Epirus, daughter of king Neoptolemus I of Epirus, the fourth wife of the king of Macedonia, Philip II, and mother of Alexander the Great...

, Cleopatra and Olympias' brother, Alexander I of Epirus

Alexander I of Epirus

Alexander I of Epirus , also known as Alexander Molossus , was a king of Epirus of the Aeacid dynasty. As the son of Neoptolemus I and brother of Olympias, he was an uncle of Alexander the Great...

 at Aegae, Philip II

Philip II of Macedon

Philip II of Macedon "friend" + ἵππος "horse" — transliterated ; 382 – 336 BC), was a king of Macedon from 359 BC until his assassination in 336 BC. He was the father of Alexander the Great and Philip III.-Biography:...

 was assassinated by the captain of his bodyguard, Pausanias. Philip's son, and previously designated heir, Alexander was proclaimed king by the Macedonian noblemen and army.* Plutarch, The Age of Alexander, p. 262-263
* Renault, The Nature of Alexander the Great, p. 61-62
* Fox, The Search For Alexander, p. 72

News of Philip's death roused many states into revolt including Thebes, Athens, Thessaly and the Thracian tribes to the north of Macedon. When news of the revolt reached Alexander he responded quickly. Though his advisors advised him to use diplomacy

Diplomacy

Diplomacy is the art and practice of conducting negotiations between representatives of groups or states...

, Alexander mustered the Macedonian cavalry of 3,000 men and rode south towards Thessaly, Macedon's immediate neighbor to the south. When he found the Thessalian army occupying the pass between Mount Olympus

Mount Olympus

Mount Olympus is the highest mountain in Greece, located on the border between Thessaly and Macedonia, about 100 kilometres away from Thessaloniki, Greece's second largest city. Mount Olympus has 52 peaks. The highest peak Mytikas, meaning "nose", rises to 2,917 metres...

 and Mount Ossa

Mount Ossa

-External links:* *...

, he had the men ride through Mount Ossa and, when the Thessalians awoke, they found Alexander at their rear. The Thessalians surrendered and added their cavalry to Alexander's force as he rode down towards the Peloponnese.* Plutarch, The Age of Alexander, p. 263
* Renault, The Nature of Alexander the Great, p. 72
* Fox, The Search For Alexander, p. 104
* Bose, Alexander the Great's Art of Strategy, p. 95

Alexander stopped at Thermopylae, where he was recognised as the leader of the Sacred League

Amphictyonic League

In the Archaic period of ancient Greece, an amphictyony , a "league of neighbors", or Amphictyonic League was an ancient association of Greek tribes formed in the dim past, before the rise of the Greek polis...

 before heading south to Corinth. Athens sued for peace and Alexander received the envoy and pardoned anyone involved with the uprising. At Corinth, he was given the title 'Hegemon' of the Greek forces against the Persians. While at Corinth, he heard the news of the Thracian rising to the north.* Renault, The Nature of Alexander the Great, p. 72

Thrace

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

Triballi

The Triballi were an ancient tribe whose dominion was around the plains of southern modern Serbia and west Bulgaria, at the Angrus and Brongus and the Iskur River, roughly centered where Serbia and Bulgaria are joined....

. He was reinforced along the way by the Agriani, a Thracian tribe under the command of Alexander's friend, Langarus

Langarus

Langarus , king of the Agrianians, was a contemporary of Alexander the Great , with whom he ingratiated himself even before the death of Philip II, previous king of Macedon. He rendered Alexander important services shortly after his accession, in his expedition against the Illyrians and...

. The Macedonian army marched up to Mount Haemus

Haemus Mons

In earlier times the Balkan mountains were known as the Haemus Mons. It is believed that the name is derived from a Thracian word *saimon, 'mountain ridge', which is unattested but conjectured as the original Thracian form of Greek Haimos....

, where they met a Thracian garrison manning the heights. The Thracians had constructed a palisade

Palisade

A palisade is a steel or wooden fence or wall of variable height, usually used as a defensive structure.- Typical construction :Typical construction consisted of small or mid sized tree trunks aligned vertically, with no spacing in between. The trunks were sharpened or pointed at the top, and were...

 of carts, which they intended to throw upon the approaching Macedonians. Alexander ordered his heavy infantry

Pezhetairoi

The pezhetairoi were the backbone of the Macedonian army and Diadochi kingdoms. They were literally "foot companions" .The Macedonian phalanxes were made up almost entirely of pezhetairoi...

 to march in loose formation and, when the carts were thrown, to either open the ranks or lay flat on the ground with their shields over them. The Macedonian archers opened fire and when the Macedonian infantry reached the top of the mountain they routed the Thracians.* Renault, The Nature of Alexander the Great, p. 73

Meanwhile, a large Triballian army led by their king, Syrmus, advanced upon the Macedonian rear. The Triballians retreated to a gorge, where they were drawn out by Alexander's light infantry

Light infantry

Traditionally light infantry were soldiers whose job was to provide a skirmishing screen ahead of the main body of infantry, harassing and delaying the enemy advance. Light infantry was distinct from medium, heavy or line infantry. Heavy infantry were dedicated primarily to fighting in tight...

. On the open ground, they were crushed by Alexander's infantry and cavalry, leaving behind 3,000 dead. The Macedonians marched to the Danube River where they encountered the Getae

Getae

The Getae was the name given by the Greeks to several Thracian tribes that occupied the regions south of the Lower Danube, in what is today northern Bulgaria, and north of the Lower Danube, in Romania...

 tribe on the opposite shore. As Alexander's ships failed to enter the river, Alexander's army made rafts out of their leather tents. A force of 4,000 infantry and 1,500 cavalry crossed the river, to the amazement of the Getae army of 14,000 men. The Getae army retreated after the first cavalry skirmish, leaving their town to the Macedonian army.* Renault, The Nature of Alexander the Great, p. 73-74

Illyria

The Siege of Pelium was undertaken by Alexander the Great against the Illyrian tribes of what is modern day Albania. 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. This was an important point of demarcation in Alexander's early reign, as it established him among the Danubian tribes to the north as a serious monarch to be reckoned with, just as he would later establish this precedent for the Greek city states under his hegemony. Taking this place allowed Alexander to march his army to southern Greece quickly, which would eventually result in the total destruction of Thebes.

Thebes

The Battle of Thebes was a battle that took place between Alexander III of Macedon and the Greek city state of Thebes in 335 BC immediately outside of and in the city proper. After having been made Hegemon of the League of Corinth, Alexander had marched to the north to deal with revolts in Illyria and Thrace, which forced him to draw heavily from the troops in Macedonia that was keeping pressure on the Greek city states of the south that was keeping them in subjection. Although Alexander did not desire to destroy the city of Thebes, after sending several embassies requesting there submission on merciful terms, he was eventually forced to destroy the city by force.

Aftermath

With the destruction of Thebes, the Macedonian possessions and vassals in Europe were once again quiscent to Alexander's rule. Alexander was now finally free to undertake the Persian campaign which had been planned for so long by his father.