It was as the Duchess of Burgundy that Margaret is mostly remembered and in this position she was undoubtedly a force to be reckoned with especially following the unexpected death of her brother Edward IV in 1483 and again two years later after the death of her last remaining brother Richard III when he died facing the forces of Henry of Richmond in 1485. Margaret did everything she could to prevent Henry Tudor's reign running smoothly, including supporting Perkin Warbeck's claim to the English throne.
Interestingly, Margaret and Warbeck both died on the same day, the 23rd November.