Today is March 17, so the obvious choice for this day in history would be the Death of St. Patrick. We're not going to talk about that though. In 1905, Franklin Delano Roosevelt wed Eleanor Roosevelt in New York. Eleanor was born in New York in 1884, her father was Theodore Roosevelt's brother. Franklin was born in Hyde Park, New York in 1882. Franklin proposed in 1903.
In 1918, Eleanor discovered Franklin was having an affair with her secretary, Lucy Mercer. Eleanor threatened to leave but Franklin's mother made an offer to support her financially if she stayed. When Franklin became president in 1933, Eleanor used her platform as First Lady to promote civil rights and humanitarian causes.
Eleanor and Franklin were fifth cousin once removed. Franklin shared great-great-great-great-grandparents with Eleanor's father (fifth cousins) and Eleanor is one generation after (once removed).