 Complete the following phrase:  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 