When the dynastic civil wars - known as the Wars of the Roses - broke out, Wiltshire fought on the Lancastrian side, becoming one of Queen consort Margaret of Anjou's staunchest supporters. He raised a significant force of Gaelic Irish troops to serve in England. He was present at the First Battle of St Albans in 1455, Battle of Wakefield in 1460, Battle of Mortimer's Cross in 1461 and the Battle of Towton.
