England
Battle of Tewkesbury, 1471
Also still in the field were the Duke of Somerset and the Earl of Devon (John Courtenay), over in Cornwall, while Jasper Tudor was raising forces in Wales. The same day as the Battle of Barnet, 14 April, Queen Margaret landed with her French forces at Weymouth.
Edward's immediate concern after Barnet was to prevent these armies from joining, so he headed west. Somerset reached Bristol safely, where he met Margaret and her son, but York was in pursuit. The Lancastrian army pressed on to Gloucester, but that town refused entry and they couldn't take time to besiege it.
They got as far as Tewkesbury, late Friday, 3 May. Edward had pursued closely for several days and both sides were exhausted. But Somerset's forces could go no further, for Edward was now too close and might catch them while on the march. The two sides were evenly matched in numbers, but York had seasoned veterans while the Lancastrian forces were largely untested.
The battle was short and sharp. As he feared, Somerset saw his men break and run when the tide turned against them and soon all was lost. Somerset lost his life at this battle, as did Courtenay and Prince Edward, the only son of Henry VI. Captured were Queen Margaret, the Countess of Devon, and Sir John Fortescue.
Tewkesbury was a tremendous victory. Between that battle and Barnet, York had eliminated his most dangerous rivals and had eliminated also his most dangerous future rival, the son of Henry VI. The Lancastrians now had no one to advocate. No one had seriously wanted the madman for a king, but so long as he had a son there was hope for the future. Tewkesbury removed that hope.