Regency and ascent of Macedon

When Alexander became sixteen years old, his tutorship came to an end. Philip, the king, departed to wage war against Byzantium. During Philip's absence, the Thracian revolted against Macedonian rule.

Alexander responded quickly,he stoped the insurgence,and founded a city named Alexandropolis.

After Philip's return from Byzantium, he dispatched Alexander with a small force to some revolts in Thrace. During another campaign Alexander is reported to have saved his father's life. Still occupied in Thrace, Philip ordered Alexander to begin mustering an army for a campaign in Greece.

Philip joined Alexander with his army in 338 BC, and they marched south through Thermopylae. They went to occupy the city of Elatea, a few days march from both Athens and Thebes.

Both Athens and Philip sent embassies to try to win Thebes's favour.

Philip marched on Amphismes, captured the mercenaries sent there by Demosthenes, and accepted the city's surrender. Philip then returned to Elatea and sent a final offer of peace to Athens and Thebes, which was rejected.

As Philip marched south, he was blocked near Chaeronea, Boeotia by the forces of Athens and Thebes. During the Battle of Chaeronea, Philip commanded the right, and Alexander the left wing, accompanied by a group of generals. Philip deliberately commanded the troops on his right wing to backstep.On the left, Alexander was the first to break into the Theban lines, followed by Philip's generals. Philip ordered his troops to press forward and quickly routed his enemy. With the rout of the Athenians, the Thebans were left to fight alone; surrounded by the victorious enemy, they were crushed.

After the victory at Chaeronea, Philip and Alexander marched into the Peloponnese welcomed by all cities. At Corinth, Philip established a "Hellenic Alliance" with the exception of Sparta. Philip was then named Hegemon of this league (known by modern historians as the League of Corinth).

After returning to Pella, Philip fell in love and married with Cleopatra Eurydice, the niece of one of his generals, Attalus. This marriage made Alexander's position as heir to the throne less secure, since if Cleopatra Eurydice bore Philip a son.

During the wedding banquet, a drunken Attalus made a speech praying to the gods that the union would produce a legitimate heir to the Macedonian throne. Alexander shouted to Attalus, "What, am I then a bastard?" and he threw his goblet at him.

Philip, who was also drunk, drew his sword and advanced towards Alexander and say : "See there, the man who makes preparations to pass out of Europe into Asia".
Alexander went away from Macedon taking his mother with him.

Alexander returned to Macedon after six months. The following year, the Persian governor of Caria, Pixodarus, offered the hand of his eldest daughter to Alexander.

Alexander reacted by sending an actor, Thessalus of Corinth, to tell Pixodarus that he should not offer his daughter's hand to an illegitimate son, but instead to Alexander. When Philip heard of this, he scolded Alexander for wishing to marry the daughter of a Carian. Philip had four of Alexander's friends, Harpalus, Nearchus, Ptolemy and Erigyius exiled, and had the Corinthians bring Thessalus to him in chains.