<human>:  Why did the Greeks win at the Battle of Gaugamela?
<bot>: The Greeks won because they were better trained, and had a better plan. The Persians were very well-trained, but they didn’t have a good plan. The Greeks were also better organized. They had a system of phalanxes that allowed them to move quickly, and they were very well-trained. The Persians had a very complicated system of infantry and cavalry, but they didn’t have a good plan.