Following the defeat of Lycophron of Pherae and Onomarchos of Phocis, Philip II of Macedon was appointed Archon of the Thessalian League; his death induced the Thessalians to attempt to throw off Macedonian hegemony, but a short bloodless campaign by Alexander restored them to allegiance.
The Thessalians were considered the finest cavalry of Greece.

The Thessalian heavy cavalry accompanied Alexander during the first half of his Asian campaign and continued to be employed by the Macedonians as allies until Macedon's final demise at the hands of the Romans.
Its organization and weaponry were similar to the Companion Cavalry, though the earlier Thessalian way of fighting emphasised the use of javelins.
The Thessalian cavalry was famed for its use of rhomboid formations, said to have been developed by the Thessalian Tagos (head of the Thessalian League) Jason of Pherae.
This formation was very efficient for manoeuvring, as it allowed the squadron to change direction at speed while still retaining cohesion.
The numbers given for Alexander's invasion of the Persian Empire included 1,800 such men.
This number would have risen no higher than 2,000.
They were typically entrusted with the defensive role of guarding the left flank from enemy cavalry, allowing the decisive attack to be launched on the right.
They often faced tremendous opposition when in this role.
At Issus and Gaugamela, the Thessalians withstood the attack of Persian cavalry forces, though greatly outnumbered.

At Ecbatana, the Thessalians with Alexander's army were disbanded and sent home.
Some remained with the army as mercenaries, yet these too were sent home a year later when the army reached the Oxus River.
Following the defeat of Lycophron of Pherae and Onomarchos of Phocis, Philip II of Macedon was appointed Archon of the Thessalian League; his death induced the Thessalians to attempt to throw off Macedonian hegemony, but a short bloodless campaign by Alexander restored them to allegiance. The Thessalians were considered the finest cavalry of Greece.
The Thessalian heavy cavalry accompanied Alexander during the first half of his Asian campaign and continued to be employed by the Macedonians as allies until Macedon's final demise at the hands of the Romans. Its organization and weaponry were similar to the Companion Cavalry, though the earlier Thessalian way of fighting emphasised the use of javelins. The Thessalian cavalry was famed for its use of rhomboid formations, said to have been developed by the Thessalian Tagos (head of the Thessalian League) Jason of Pherae. This formation was very efficient for manoeuvring, as it allowed the squadron to change direction at speed while still retaining cohesion. The numbers given for Alexander's invasion of the Persian Empire included 1,800 such men. This number would have risen no higher than 2,000. They were typically entrusted with the defensive role of guarding the left flank from enemy cavalry, allowing the decisive attack to be launched on the right. They often faced tremendous opposition when in this role. At Issus and Gaugamela, the Thessalians withstood the attack of Persian cavalry forces, though greatly outnumbered.
At Ecbatana, the Thessalians with Alexander's army were disbanded and sent home. Some remained with the army as mercenaries, yet these too were sent home a year later when the army reached the Oxus River.
Ancient Macedonian army