"Thunderer", the fifth ship of her name to serve in the Royal Navy, was laid down on 26 June 1869 at Pembroke Dockyard, Wales. Construction was subsequently halted for a time in 1871 to modify the ship to improve her stability and buoyancy by extending the breastwork to cover the full width of the hull which increased the ship's freeboard amidships and provided additional accommodation for the crew. The ship was launched on 25 March 1872 by Mrs. Mary Meyrick, wife of Thomas Meyrick, MP. Two years later she was transferred to Portsmouth Dockyard to finish fitting out.