Tourney at Storm's End
Ser Barristan Selmy recounts that Prince Rhaegar Targaryen once rode brilliantly in a tourney at Storm's End, defeating Lord Steffon Baratheon, Lord Jason Mallister, Prince Oberyn Martell, a mystery knight who turned out to be Simon Toyne, and, after breaking twelve lances, Ser Arthur Dayne. However, Rhaegar was defeated by a knight of the Kingsguard in the champion's tilt.
As the Lord Commander of the Kingsguard, Gerold Hightower wrote in the White Book that Lord Steffon's tourney took place at Storm's End, in which Barristan Selmy was named champion after unhorsing Lord Robert Baratheon, Prince Oberyn, Lord Leyton Hightower, Lord Jon Connington, Lord Jason, and Prince Rhaegar.
Prince Rhaegar Targaryen defeated Lord Steffon Baratheon
Prince Rhaegar Targaryen defeated Lord Jason Mallister
Prince Rhaegar Targaryen defeated Prince Oberyn Martell
Prince Rhaegar Targaryen defeated Simon Toyne
Prince Rhaegar Targaryen defeated Ser Arthur Dayne
Ser Barristan Selmy defeated Lord Robert Baratheon
Ser Barristan Selmy defeated Prince Oberyn Martell
Ser Barristan Selmy defeated Lord Leyton Hightower
Ser Barristan Selmy defeated Lord Jon Connington
Ser Barristan Selmy defeated Lord Jason Mallister
Ser Barristan Selmy defeated Prince Rhaegar Targaryen
Lord Steffon Baratheon was sent on a mission to Essos in 278 ᴀᴄ, but he died during the return voyage. The tourney he hosted thus must have occurred by 278 AC at the latest. Barristan states that Rhaegar Targaryen defeated Simon Toyne during the tourney, but Barristan's White Book entry lists the tourney as occurring after the defeat of the Kingswood Brotherhood (during which Barristan killed Simon) and before the Battle of the Trident. In the White Book entry, written by Ser Gerold Hightower (as he was the Lord Commander), the tourney is called "Lord Steffon's Tourney". The chronology of the entry would place the tourney years after Steffon's death, which is suggested as well by naming Robert Baratheon by the title of "Lord", as Robert became the Lord of Storm's End after Steffon's death, and possibly the fact that Jon Connington was described as "Lord" as well, while it is known that Connington (exiled during Robert's Rebellion, ruled Griffin's Roost as Lord only for a few short years.
When the discrepancy was brought to his attention, George R. R. Martin stated that Barristan's recollection of Simon's participation is incorrect and that the aged knight is confusing multiple historical tourneys. It seems therefore likely that Barristan mixed up multiple tourney's at Storm's End in his mind, one hosted by Lord Steffon before his death, and one hosted by Robert after Steffon's death.