This victor at the Battle of Barnet, whose sons became the "Princes in the Tower," defended his throne against Margaret of Anjou at the Battle of Tewkesbury.
He's not William the Conqueror, but this king established the Council of Wales and the Marches at Ludlow Castle in order to govern Wales. This king's brother claimed Ankarette Twynyho had poisoned Isabel Neville, for which he was allegedly drowned by this king in a barrel of malmsey wine. This king was paid seventy five thousand crowns in the Treaty of Picquigny and was betrayed by his brother, the Duke of Clarence, who sided with the Earl of Warwick. This victor at the Battle of Barnet, whose sons became the "Princes in the Tower," defended his throne against Margaret of Anjou at the Battle of Tewkesbury. For 10 points, name this first Yorkist King of England.
He's not William the Conqueror, but this king established the Council of Wales and the Marches at Ludlow Castle in order to govern Wales.
Edward IV of England [prompt on Edward of York]