Robert Baratheon came to control the Iron Throne after successfully overthrowing the Targaryen empire in what was known as Robert’s Rebellion. His most famous moment during that battle was to kill Rhaegar Targaryen at the Trident. The incentive for Robert’s rebellion was based on a couple of different scenarios one being the murder of Ned Stark’s father and brother at King’s Landing where the Mad King had them roasted alive. And then the apparent kidnap and rape of Lyanna Stark at the hands of Rhaegar Targaryen. Robert sits on the iron throne for 15 years before he succumbs to the treachery of his wife Cersei Lannister. He leaves behind many bastard children including Gengry and Miranda.