Alexander tamed the wild horse Bucephalus at age 12, an enormous stallion with a furious demeanor. The horse then became his battle companion for most of Alexander’s life. When Alexander was 16, Alexander's father, Phillip, went to battle the Byzantiums and left him in charge of Macedonia. Alexander saw a chance to prove his worth. He led a cavalry against against the Sacred Band of Thebes, a supposedly unbeatable, select army. In 336 B.C., Alexander’s father, the king Phillip, was assassinated. At age 20 he became king. Alexander killed all rivals before they could challenge his sovereignty. He quenched rebellions for independence in Greece, and followed in his fathers footsteps in his hunger for world domination. He went for Persia, and easily conquered Sardes. Alexander's army ran into a bump, when they got some resistance in the cities of Miletus, Mylasa and Halicarnassus. Halicarnassus held out long enough for King Darius III, the Persian king, to amass a large army. In 333 B.C., Alexander and his men encountered a massive Persian army led by King Darius III near the town of Issus in Turkey. Alexander's men were outnumbered, but had more experience and determination. It became clear that Alexander would win, and King Darius III fled. Alexander took over Egypt and Tyre, and proclaimed himself the King of Persia. When Alexander entered India is beloved horse Bucephalus died. He returned to Persia, and offered to marry Persian princesses at a mass wedding. He had plans to take over Arabia, but did not live to see that happen. He died in June 323 B.C. at age 32.