Alexander didn't just order charges; he led them. He was personally wounded eight times. He shared the same food, slept on the same hard ground, and suffered the same thirst as his soldiers.
When his army was dying of thirst in the Gedrosian Desert, a soldier brought Alexander a helmet full of water. In front of the entire army, Alexander poured it into the sand, refusing to drink while his men could not.
By being at the point of impact, Alexander could see the battle unfold in real-time. He didn't rely on messengers; he saw the gap in the Persian line at Gaugamela with his own eyes and exploited it instantly.