Found an account of a steamboat accident (click here) in 1865 that killed 1,700 people. The majority of the fatalities were Union soldiers who had just been released from Andersonville Prison and were on their way home.
The nature of the accident sounded very similar to the USS Tulip accident that occurred in our neck of the woods in 1864 click here. The Tulip was in the Potomac River when a boiler exploded and killed 49 Union soldiers. The following is from Wikipedia:
There is a USS Tulip memorial site in St. Inigoes next to the manor house currently owned by Ted Koppel. Head towards Webster Field on Villa Road, and follow “Civil War” signs to the Memorial. As the headline states in one of the linked stories above “The memorial is small; the story is important.” The story also explains how the memorial came to be located adjacent to Cross Manor.