They retained the broadside ironclad layout of their predecessor, but their sides were fully armoured to protect the 50 guns they were designed to carry.

[4] Agincourt was considered "an excellent sea-boat and a steady gun platform, but unhandy under steam and practically unmanageable under sail"[5] as built.

[6] Agincourt had one 2-cylinder horizontal return connecting rod-steam engine, made by Maudslay, driving a single propeller using steam provided by 10 rectangular fire-tube boilers.

It produced a total of 4,426 indicated horsepower (3,300 kW) during the ship's sea trials on 12 December 1865 and Agincourt had a maximum speed of 13.55 knots (25.09 km/h; 15.59 mph).

The ship carried 750 long tons (760 t) of coal,[7] enough to steam 1,500 nautical miles (2,800 km; 1,700 mi) at 7.5 knots (13.9 km/h; 8.6 mph).

[8] In a series of technical articles he wrote on the armoured vessels of the mid-Victorian Navy, for the quarterly Mariner's Mirror, Admiral George A. Ballard described Agincourt and her sisters as "the dullest performers under canvas of the whole masted fleet of their day, and no ships ever carried so much dress to so little purpose.

[6] In 1907 the upper portions of one of her masts was installed at the shore establishment HMS Ganges for use in the training of boy seamen.

The lengthy delay in completion was due to frequent changes in design details, and experiments with her armament and with her sailing rig.

[16] Agincourt's first assignment, together with her half-sister[Note 2] Northumberland, was to tow a floating drydock from England to Madeira where it would be picked up by Warrior and Black Prince and taken to Bermuda.

The ships departed the Nore on 23 June 1869, loaded down with 500 long tons (510 t) of coal stowed in bags on their gun decks, and transferred the floating dock 11 days later after an uneventful voyage.

[18][19] Agincourt was stuck fast and had to be lightened; her guns were removed and much of her coal was tossed overboard before she was towed off by Hercules, commanded by Lord Gilford, four days later.

"[20][21] In 1873, Vice Admiral Sir Geoffrey Hornby, commander of the Channel Squadron, transferred his flag to Agincourt as her sister Minotaur, his former flagship, was taken in hand for a refit that lasted until 1875.

After those tensions faded, the ship returned to the Channel, where she served as second flag until 1889 including during Queen Victoria's Golden Jubilee Fleet Review in 1887.

After five ignominious decades as what naval historian Oscar Parkes called "a grimy, dilapidated and incredibly shrunken relic"[24] of her former self, she was scrapped beginning on 21 October 1960.