This line was founded by Prince Ludwig August, second son of Prince August of Saxe-Coburg and Gotha and Princess Clémentine of Orléans, who on 15 December 1864 married in Rio de Janeiro Princess Leopoldina of Brazil. They had four sons; for a time, their two eldest sons, Princes Peter August and August Leopold, were heirs presumptive to the Brazilian throne. After the fall of the Brazilian monarchy in 1889, the family returned to Europe. Prince Rainer, who was appointed head of the house in 1921, was son of Prince August Leopold and grandson of Prince Ludwig August.