She was built in Hull at the William Gibson Shipyard, as one of a class of three (the others being "Combatant" and "Valorous") and launched in 1804. Designed by John Staniforth MP, they were flush-decked, shallow draught and (for their dimensions) heavily armed. Rated as a sloop, she had a design based on the Danish "Praam" (English "Pram"), allowing the combination of heavy armament with a draught of only 11 feet. Her design may well have been influenced by the flush-decked, shallow draught vessels of Napoleon's invasion fleet, although "Dauntless" and her sisters were significantly larger. The Royal Navy rated her for purposes of command as an 18-gun sloop, but as a captain's command until 1806.