Alexander the Great was a king of Macedon in northern Greece who conquered much of the known world in the 4th century BC. He had a strong army developed by his father Philip that utilized innovative tactics like the sarissa pike and coordinated cavalry attacks. Alexander succeeded his father at age 20 and spent over a decade conquering the massive Persian Empire. By the time he died at age 32, his empire stretched from Greece to modern-day Pakistan. He founded many cities and was considered one of the greatest military commanders in history due to his undefeated record in battle.