St. Mary’s County Museum Division will host a special remembrance ceremony Sunday, April 26, 2026, at 2 p.m. at the St. Clement’s Island Museum to honor the 87 lives lost in the Black Diamond Disaster, a little-known Civil War maritime tragedy that occurred near St. Clement’s Island on April 23, 1865.
The event marks the 161st anniversary of the collision between the barge Black Diamond and the steamer Massachusetts in the Potomac River. The Black Diamond had been stationed on picket duty off St. Clement’s Island as part of the hunt for John Wilkes Booth following the assassination of President Abraham Lincoln. The Massachusetts was traveling from Alexandria, Virginia, to Fortress Monroe when it struck the Black Diamond in darkness. The barge sank in under three minutes.
A wreath-laying ceremony will take place at the museum site located at 38370 Point Breeze Road in Colton’s Point. At 2:30 p.m., guests will move to nearby Potomac Gardens for a concert and reception featuring the 8th Green Machine Regiment Band, an early American brass ensemble that performs 19th-century music on authentic period instruments.
Attendees will also have the opportunity to meet Karen Stone, St. Mary’s County Museum Division manager and author of “Shipwreck on the Potomac: Disaster in Pursuit of Lincoln’s Killer,” during a book signing. Stone’s book provides the first detailed account of the incident.
Later that evening, the 2026 Dinner and a Cruise Series will launch with a ticketed program titled “The Potomac River and John Wilkes Booth.” Local author and Booth historian Michael Kauffman will discuss the river’s strategic importance during the Civil War and its role in Booth’s escape attempt. The cruise departs from the St. Clement’s Island Museum area aboard a water taxi.
For information or to reserve cruise tickets, contact the St. Clement’s Island Museum at 301-769-2222 or visit its Facebook page at Facebook.com/SCIMuseum.
The Black Diamond Disaster claimed the lives of 83 passengers and crew from the Massachusetts plus four from the Black Diamond. Many victims were recently freed Union soldiers or civilian volunteers serving on the vessel. Bodies of some victims were never recovered. The tragedy occurred just days after Lincoln’s assassination and received limited attention at the time amid national mourning and the larger manhunt.
In addition to the April 26 events, the St. Mary’s County Museum Division is resuming its monthly “Second Saturday” activities at three sites throughout 2026. These free programs, included with regular museum admission, encourage hands-on exploration of nature through play and discovery for all ages.
Scheduled activities include:
At Piney Point Lighthouse Museum, 44720 Lighthouse Road in Piney Point:
- May 9, 2026, 10 a.m. to noon: Honoring Mother Earth – A Community Cleanup and Sustainable Living Program
- July 11, 2026, 10 a.m. to noon: Helping Backyard Birds – Learn About Local Birds and Build a Feeder
- October 10, 2026, 10 a.m. to noon: Batty for Bats – Decorate Your Own Bat Box
- November 14, 2026, 10 a.m. to noon: Deck the Halls – A DIY Ornament Workshop
At the U.S. Colored Troops Interpretive Center at Lexington Manor Passive Park in Lexington Park:
- June 13, 2026, 10 a.m. to noon: Freedom Walk – A Reflective Community Stroll in Honor of Juneteenth
At St. Clement’s Island Museum:
- August 8, 2026, 10 a.m. to noon: Paint Scenery Using Water from the Potomac River
Participants of all ages are welcome. Adults are encouraged to join children in simple, relaxing outdoor experiences. Call ahead for details and weather updates. Walk-ups are encouraged.
For group educational visits or additional program information, contact Olivia Flack at Olivia.Flack@stmaryscountymd.gov. Museum hours, admission prices and full event calendars are available on the division’s Facebook pages: Facebook.com/SCIMuseum, Facebook.com/USCTCenter and Facebook.com/1836Light.
These programs highlight St. Mary’s County’s rich maritime and Civil War history while connecting residents to the natural environment along the Potomac River. The Black Diamond remembrance and Second Saturday series offer opportunities for families, history enthusiasts and nature lovers to engage with local heritage in meaningful ways.
The April 26 events provide a focused look at a tragedy that unfolded in Southern Maryland waters during one of the most dramatic weeks in American history. The Potomac River served as both a barrier and a pathway during Booth’s flight, making the area central to the national story.
St. Mary’s County museums continue to preserve and share these stories through exhibits, living history and community programs. The combination of remembrance, music, author talks and hands-on activities creates accessible entry points for learning about the region’s past.
