Watch Free Online HD Moviesjoy. Over 2000 Union soldiers, passengers and crew were crammed aboard the steamboat Sultana, licensed to carry 376. Graft, greed, overcrowding, a poorly maintained boat, and the Mississippi River was swollen with spring snowmelt conspired together to create a disaster. On April 27, 1865, the boat’s boilers exploded, causing the worst maritime disaster in US history.