 Walter Devereux and William Herbert were assigned to raise an army in Gloucestershire, Herefordshire, Shropshire, and the marshes of Wales to attack the rebels; and on 14 August 1468, Harlech castle finally surrendered to the Yorkists.In 1468 Edward IV announced his intent to invade France.On 3 August 1468 Walter Devereux was assigned to muster at Gravesend with his men for service overseas, but other events in the kingdom prevented this from occurring.