During his youth, Alexander was tutored by Aristotle until age 16. After Philip's assassination in 336 BC, he succeeded his father to the throne and inherited a strong kingdom and an experienced army. Alexander was awarded the generalship of Greece and used this authority to launch his father's pan-Hellenic project to lead the Greeks in the conquest of Persia. In 334 BC, he invaded the Achaemenid Empire (Persian Empire) and began a series of campaigns that lasted 10 years. Following the conquest of Anatolia, Alexander broke the power of Persia in a series of decisive battles, including those of Issus and Gaugamela. He subsequently overthrew Persian King Darius III and conquered the Achaemenid Empire in its entirety. At that point, his empire stretched from the Adriatic Sea to the Beas River.