Epitomising the start of an era of radical change in warship design, this work perfectly illustrates the position in which the Royal Navy found itself when the steam-powered warship came of age in the late 1860's. The ironclad hull had been de rigeur since the launch of H.M.S. Warrior in 1860, guns had vastly increased in calibre and were now being grouped in turrets for greater firepower, and engines were at last reliable enough for sails to be abandoned completely. The first ships to combine all these features -Devastation and Thunderer - were ordred and laid down in 1869 and their completion during the following decade signalled the beginnings of the truly modern battlefleet.
H.M.S. Thunderer, one of the original pair of sea-going "mastless" turret-ships in the Royal Navy, was built at Pembroke, launched on 25 March 1872 and eventually completed in May 1877 at a cost of (368,428. Displacing 9,330 tons and measuring 285 feet in length with a 62½ foot beam, she was protected by a total of 2,540 tons of armour plating and was armed with two massive 35-ton and a similar pair of 38-ton muzzle-loading guns. A contemporary writer likenend her to "an impregnable piece of Vauban fortification with bastions mounted upon a fighting coat mine" and she was undeniably impressive, especially when in a seaway at full speed. With bunker capacity for 1,800 tons of best coal and horizontal direct-acting Humphreys and Tennant engines producing 6,270 i.h.p., she could make 12½ knots when required but had an excellent radius of 4,700 miles at 10 knots when steaming normally. Initially commissioned with the Reserve Fleet Particular Service Squadron, she was then sent out to the Mediterranean in the autumn of 1878 where she remained until 1886. Returning home, she underwent several refits but was mostly held in Reserve thereafter apart from a brief return to the Mediterranean from March 1891 to September 1892. After five years as portguard ship at Pembroke from 1895 to 1900, she joine the Fleet Reserve at Chatham until made non-effective in 1907 and was finally sold for breaking in 1909.
By the time Thunderer was first commissioned in 1877, those few "wooden walls of Old England" still afloat had long since finished their active service and were mostly ending their days as training ships. Such a vessel is portrayed here off the new battleships's starboard bow and her complement of young cadets seem to be crowding the veteran's ratlines in order to have a better view of the awesome ironclad to which they all aspired.