In the days following President Lincoln’s assassination, a lesser-known tragedy unfolded on the Potomac River. As the nation grappled with the loss of its leader and the hunt for his killer intensified, a collision between two vessels resulted in the deaths of 87 people, including recently freed Union soldiers and civilian volunteers. This is the story of the Black Diamond disaster – a tale of sacrifice, duty, and unforeseen consequences in the pursuit of justice.  This tragedy unfolded on April 24, 1865, when a large sidewheel steamer, known as the “Massachusetts,” collided with the coal barge “Black Diamond” on the Potomac River. The disaster occurred at approximately 1:00 a.m. as the steamer navigated from Alexandria to City Point, Virginia. In total, 87 lives were lost, including four United States Quartermaster Department employees who were later laid to rest in the Alexandria National Cemetery.  Historian and author Karen Stone will help us understand this little-known local disaster.