Martin Darwin and Mary Kidd are my 2xgreat grandparents-- I have stacks of info.They married earlier than the date you have, though:24 April 1866 (reported in the Yorkville Enquirer for 3 May 1866), this was very likely the first anniversary of Martin's return to SC from Confederate service (he was 1st Lieutenant, Co. B, 12th Regiment South Carolina Volunteers:wounded at 2nd Manassas, paroled at Appomattox).Mary Kidd apparently hailed from Tennessee, but I haven't done her family tree yet.
Martin's parents were John Bland Darwin and Gilly Sandlin, his grandparents John Darwin (1755-1832; his revolutionary war pension application is available from the US National Archives), great-grandparents were William Darwin (1707-1786) and Jane (?Wilkinson), of Lousia County, Virginia -- before that, it gets controversial.
Martin and Mary's children were: 1. Ellis (1867-1932 - my great-grandfather) 2. William Henry (1868-1878) 3. Gilly Jane (1871-1934) 4. Robert Oscar (1872-?) 5. James Madison (?-?) 6. Wade Hampton (1876-1931) 7. Martin Samuel (1878-1880) 8. Caroline Lee (1881-1914) 9. Mary A. (1883-1927) 10. Sarah L. (1886- ?) 11. Augustus W. (1890- ?)
Hope this is enough to help you get started -- write me if you would like more info.Best wishes, Tim D. Grana