Which 1868 Wilkie Collins novel is about a mysterious stolen gem?

Which Union general led the 1865 march through the Carolinas after his "March to the Sea"? In April 1865, Jefferson Davis and most of his cabinet fled which capital city? Who reportedly shouted "Sic semper tyrannis! The South is avenged!" in 1865? In 1868, which president granted an unconditional pardon to all who had rebelled in the Civil War? Which Paris music hall, famous for risque revues, opened in 1869? Along with James Fisk, which financier tried to corner the gold market, causing 1869's "Black Friday"? Who commands the submarine Nautilus in Jules Verne's 1870 novel? Which title heroine remembers the man run down by a train on the day she first met Vronsky?