According to The History Channel (and every other source I could find):
September 8, 1974
President Ford pardons former President NixonOn this day in 1974, President Gerald Ford, who assumed office on the heels of President Richard M. Nixon’s resignation, pardons his predecessor for his involvement in the Watergate scandal.
TRUNCATED: Read more here.
When one is looking for an image to illustrate a story, sometimes it's hard to choose just one. Here's a small (Rogue's) Gallery: