Alexander became king of Macedonia in 336 BC when his father was assassinated. A meeting was held to the of Greek cities made him "strategos" (General or supreme commander). He used this authority to launch his father's military expansion plans. In 334 BC, he invaded Persian-ruled Asia Minor. He began series of campaigns that lasted ten years. Alexander broke the power of Persia in a series of decisive battles, most notably the battles of Issus and Gaugamela. He overthrew the Persian King Darius III and conquered the entire Persian Empire. He married the king's daughter to symbolize the unity of his new empire. At that point, Alexander's empire stretched from the Adriatic Sea to the Indus River.