The launch of a new ship is usually a spectacle, but when the floating battery HMS Aetna was launched it was a spectacle seldom seen. The ship was being constructed by John Scott Russell & Company at Millwall, London and was scheduled to be launched on Saturday May 5, 1855, however at about 9 p.m. on the evening of May 3, 1855 the wood hull of the 1,469 ton Aetna caught fire. Soon after the fire was detected a floating engine was brought down from HM Dockyard and was attending to the flames. Aetna burned out of control and it was feared that the two ships alongside of her would also be set alight. Other floating fire equipment was dispatched and their hoses were soon brought to bear on the burring vessel and the other ships on the slip.

At about 11 p.m. without warning Aetna broke free of the slipway and launched herself into the Thames to the horror of hundreds of people in boats at the mouth of the dockyard. A number of people panicked and jumped into the water fearing that the flaming hulk would turn turtle and crush them in their small boats. Fortunately for everyone Aetna did not capsize and everyone was safely pulled from the water. The fire burned until sometime the following day and Aetna was a total loss, the other two ships sustained some damage, but were repaired. Aetna, the ship that launched itself, was scrapped on the banks of the Thames.