Passage: The Act of Accord and the events of Wakefield left the 18-year-old Edward, Earl of March, York's eldest son, as Duke of York and heir to his claim to the throne. With an army from the pro-Yorkist Marches (the border area between England and Wales), he met Jasper Tudor's Lancastrian army arriving from Wales, and he defeated them soundly at the Battle of Mortimer's Cross in Herefordshire. He inspired his men with a "vision" of three suns at dawn (a phenomenon known as "parhelion"), telling them that it was a portent of victory and represented the three surviving York sons; himself, George and Richard. This led to Edward's later adoption of the sign of the sunne in splendour as his personal device.

Question: What sign did Edward adopt?
sign of the sunne