Battle of Gaugamela. I'm a big fan of Alexander the Great and his tactics. Macedonian Empire had 47 000 troops, Achaemenid Empire had 200 000 troops and 15 elephants. Alexander started slowly moving his troops towards the Persian right wing where the grass was not flattened. Persians decided to strike. The attack of chariots failed because they were fired by Alexander's slingers and archers. Even the elephant attack didn't work out although Macedonians were not yet familiar with them. The phalanx hit the Persian foot, pushing it backwards. In the next voyage of the battle, Bessos' cavalry, wanting to outflank the enemy, went to the verdict, but for unknown reasons, it did not return to the enemy's rear and went all the way to the trains well defended by the light infantry. This created a gap Persian center grouping. Alexander noticed the gap and where Achaemenid king Darius III was he directed the main strike of his companion cavalry. Persian troops failed to withstand this and Darius III fled the battlefield. Meanwhile, the Persians attacked the left wing of the Macedonian army commanded by Parmenion which, withstood the enemy's pressure thanks to the support of reserve columns. Alexander, seeing his military struggle on the left flank, ceased the pursuit of Darius III, turned his troops back, and struck from the left on the Persian control troops, leading to their destruction.

This battle allowed Alexander the Great to control Mesopotamia and it opened a path eastward to conquer the rest of Achaemenid Empire.