The most significant accomplishment for Alexander was that he was able to conquer more territory than any other general before him. He is also credited as having never lost a battle. This has been attributed to the battle tactics that he employed, which were far advanced than his enemies.
He was a brilliant tactician. Before he became king of Macedonia, as a young man of 16, he was putting down uprisings. But after he became king, he dealt with those who were rebellious close to home, and after building a large army, set out to take possession of the lands around him.
He crossed into what is now Asia and conquered the Persian empire. He marched his men through over 17,000 km, taking one nation after another. No other king or general had managed to do as much as Alexander, especially in such a short time. He reigned over his empire for 12 years, before he died under mysterious circumstances. After his death, the four generals underneath him divided the territories amongst each other.