None of John's three other sons would marry in his lifetime. Infante Alexandre died at the age of five, and Infante Carlos died at the age of twenty without any marriage proposals or children. Only Infante Pedro would live long enough to marry, but John did not live long enough to see it. Infante Pedro married the daughter of his older brother King José I, Princess Maria Francisca, Princess of Brazil, on 6 June 1760. When Princess Maria became Queen Maria I of Portugal upon the death of her father, King José I (John's son), Prince Pedro became King Pedro III, following Portuguese royal law that if the consort of a queen regnant produced children with the queen regnant, he would become king of Portugal "jure uxoris".