So who was this guy, who started Islam? Exiled from his home tribe, he formed an army: "there were epic battles with the Quraysh and other tribes, and Muhammed was a fighter and tactician." His military abilities, both to lead soldiers, and to use sword himself, became legendary. After the battle of Badr, he ordered the unarmed prisoners to be executed. He ordered several poetesses and poets in Medina to be killed, because they had expressed doubts about him. He organized the murders of several hundred men in the town of Banu Qurayza, suspecting them of disloyalty.
His family relationships were sometimes problematic: desiring "the wife of his adopted adult son," he took "her to be his fifth wife." He seemed to have a total of somewhere between eleven and thirteen wives, of who the youngest was engaged to him at age six, although she did marry him until she was nine years old.
(Quotes from Karen Armstrong at the University of London, and Laurie Goodstein of the New York Times.)