When Elizabeth Woodville's relatives, especially her brother Anthony Woodville, 2nd Earl Rivers, began to challenge Warwick's pre-eminence in English political society, Warwick conspired with his son-in-law George, Duke of Clarence, the king's younger brother. One of his followers accused Elizabeth Woodville's mother, Jacquetta of Luxembourg, of practising witchcraft. She was acquitted the following year. Warwick and Clarence twice rose in revolt and then fled to France. Warwick formed an uneasy alliance with the Lancastrian Queen Margaret of Anjou and restored her husband Henry VI to the throne in 1470. But the following year, Edward IV, returned from exile and defeated Warwick at the Battle of Barnet, and the Lancastrians at the Battle of Tewkesbury. Henry VI was killed soon afterwards.