The worst maritime disaster in American history was the explosion of the Sultana on the Mississippi in April, 1865. As many as 2300 recently released Union prisoners of war were killed.

www.thedisastersongproject.com/sultana.html
for an abbreviated version of the story and the lyrics (this one's an original)

You can also hear the tune at http://soundcloud.com/jon-waterman-2/sultana