They differed from the prototype by being constructed of "fir" (actually, pitch pine) rather than oak, and mounted an extra (fourteenth) pair of 24-pounder guns on the upper deck forward. All would be reclassified as 50-gun fourth-rate frigates in February 1817; however, the use of softwood in their construction was such that they were only intended for a short lifetime, and indeed all five were taken to pieces after a few years' service. The first pair were originally ordered on 4 May 1812 as Tagus and Eridanus of the 18-pounder armed , but were renamed on 7 January 1813 as and . The War of 1812 broke out in June, and on 26 December two further ships were ordered, becoming and . The final ship was , ordered on 7 January 1813. These five new ships were of a slightly modified design, having ports for 28 instead of 26 × 24-pounders and were built of softwood, to speed up the construction. The ships were launched from June 1813 to February 1814. Principal characteristics There were small variations in the dimensions of the different ships: Length on gundeck: 159 feet 2 inches Beam: 41 feet 11 inches Tonnage: 1246 to 1277 tons Established armament: 28 (Endymion 26) × 24-pounders, 20 × 32-pounder carronades, 2 × 9-pounder chase guns Complement: 340 men Rated: 40-gun fifth-rates, rerated as 50-gun fourth-rates in 1817. List of ships Frigate classes Fifth-rate frigates of the Royal Navy Ship classes of the Royal Navy