The "Thames"-class frigate was a 32-gun fifth-rate frigate class of eight ships of the Royal Navy based on the "Richmond"-class frigate designed by William Bately. The ships were ordered to the older design, which was of a smaller type of ship compared to more modern designs, so that they could be built quickly and cheaply in time to assist in defending against Napoleon's expected invasion of Britain. The class received several design changes to the "Richmond" class, being built of fir instead of oak, with these changes making the class generally slower and less weatherly than their predecessors, especially when in heavy weather conditions. The first two ships of the class, "Pallas" and "Circe", were ordered on 16 March 1804 with two more ordered on 1 May and the final four on 12 July. The final ship of the class, "Medea", was cancelled on 22 October before construction could begin but the other seven ships of the class were commissioned between 1804 and 1806.