 Greener assisted Daniel Henry Chamberlain in Whittaker's defense during the court-martial.From 1876 to 1879 he represented South Carolina in the Union League of America and was president of the South Carolina Republican Association in 1887 and was active in freemasonry.From 1885 to 1892, Greener served as secretary of the Grant Monument Association, where he is credited with having led the initial fundraising effort  that eventually brought in donations from 90,000 people worldwide to construct Grant's Tomb, still the largest mausoleum in North America.