Alexander the great did not conquer Greece.
Greece was a collection of independent city-states, most of which were conquered by Alexander's father, Philip of Macedon. Alexander inherited Greece from his father.
The attack was no surprise - the two armies were confronting each other. Alexander wanted to defeat the Persian army to gain control of the Persian empire.
There could be no surprise. His father Philip 2 had been planning and preparing an invasion of the Persian Empire for several years, and on his assassination his son Alexander took over and got it rolling again. The Persians knew what was coming and had enrolled 10,000 Greek mercenaries to bolster their army. All that changed was that the Macedonian invasion by Alexander was delayed for a year as he had to put down revolts in Greece to secure his rear. The well-aware Persians waited.
Revolution in Greece led by Thebes. He sold their people into slavery as a warning to the other city-states.
Alexander the Great defeated Darius, king of Persia in 331 BCE. This was at the battle Gaugamela, he did march through Bactria in 329 BCE, but he had already defeated the Persians.
Alexander's empire had no contact with Central Europe. The Persians remained in Persia.
Ferociously.
Alexander the Great.
Alexander the Great .
With their cavalry.
Alexander the great
Gaugamela.
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