The Duke of Lancaster is a title in the British peerage, traditionally held by the reigning monarch. It is associated with the historic county of Lancashire in England. The title has significant historical importance, dating back to the 14th century, and is linked to the House of Lancaster, which played a key role in the Wars of the Roses. Currently, the title is held by the reigning monarch, who exercises certain rights and privileges associated with it. The Duke of Lancaster also oversees the Duchy of Lancaster, a portfolio of land, property, and assets that generates income for the royal family.