By 1640, Portugal was on the verge of rebellion against Spanish-based Habsburg rule, and a new Portuguese king had to be found. The choice fell upon John, 8th Duke of Braganza, who had a claim to the throne of Portugal both through his grandmother Catherine of Guimarães, a legitimate granddaughter of King Manuel I, and through his great-great-grandfather, the 4th duke of Braganza, a nephew of King Manuel I. John was a modest man without particular ambitions to the crown. Legend has it that his wife Luisa of Guzman urged him to accept the offer by saying, "I'd rather be queen for one day than duchess for a lifetime". He accepted the leadership of the rebellion against Spain, which was successful, and was acclaimed King John IV of Portugal on 1 December 1640.