Robert Fulton
The first successful trial run of a steamboat had been made several years earlier in the United States by inventor John Fitch, on the Delaware River on August 22, 1787. Attendees included delegates from the Constitutional Convention, who were observing while taking a break from their summer-long sessions at Independence Hall. The steamboat was propelled by a bank of oars on either side of the boat. The following year Fitch launched a boat powered by a steam engine driving several stern-mounted oars. These oars paddled in a manner similar to the motion of a swimming duck's feet. With this boat he carried up to thirty passengers for hire on numerous round-trip voyages on the Delaware River between Philadelphia and Burlington, New Jersey.
French battleship Napoléon
The United Kingdom already had a few coastal units with screw/steam propulsion in the 1840s, called "blockships", which were conversions of small traditional battleships into floating batteries with a jury rig, with a medium engine for speeds of to . The Royal Navy had also commissioned a number of steam sloops, being the first screw-propelled warship to be launched anywhere in the world in 1843. Both nations had also developed steam frigates, the French launched in 1845, and the British a year later. However, "Napoléon" was the first regular steam battleship to be launched.
In 1847, Britain had designed a screw/steam battleship named , but the project much delayed and she did not enter service until 1854. Her sister ship, was ordered in 1849 and commissioned in January 1853. Another sailing battleship, was converted to steam on the stocks and launched in March 1851; she beat "Agamemnon" into service in November 1852. Britain’s reluctance to commit to the steam battleship apparently stemmed from her commitment to long-distance, worldwide operation, for which, at that time, sail was still the most reliable mode of propulsion.