Murders of Harry and Harriette Moore
Harry T. Moore and his wife, Harriette V. S. Moore, were pioneer activists and leaders of the early Civil Rights Movement in the United States and became the first martyrs of the movement. On the night of Christmas, December 25, 1951, a bomb that had been planted under the bedroom floor of the Moores' home in Mims, Florida, exploded.
Source: Wikipedia — Murders of Harry and Harriette Moore (CC BY-SA 4.0)