The Kongō-class ironclads (金剛型) were a pair of armored corvettes built for the Imperial Japanese Navy (IJN) by British shipyards in the 1870s.

Tensions between Japan and China heightened after the former launched its punitive expedition against Taiwan in May 1874 in retaliation of the murder of a number of shipwrecked sailors by the Paiwan aborigines.

The Japanese terminated the negotiations with the Brazilians in October after the ship was badly damaged upon launching and the expeditionary force was about to withdraw from Taiwan.

The crisis illustrated the need to reinforce the IJN and a budget request was submitted that same month by Acting Navy Minister Kawamura Sumiyoshi for ¥3.9–4.2 million to purchase three warships from abroad.

Nothing was done until March 1875 when Kawamura proposed to buy one ironclad for half of the money authorized and use the rest for shipbuilding and gun production at the Yokosuka Shipyard.

No response was made by the Prime Minister's office before the proposal was revised to use all of the allocated money to buy three ships, one armored frigate and two armored corvettes of composite construction to be designed by the prominent British naval architect Sir Edward Reed, formerly the Chief Constructor of the Royal Navy.

[3] Commander Matsumura Junzō arrived in London on 21 July and gave Reed the specifications for the ships.

Reed responded on 3 September with an offer, excluding armament, that exceeded the amount allocated in the budget.

Ueno signed the contracts for all three ships on 24 September despite this problem because Reed was scheduled to depart for a trip to Russia and the matter had to be concluded before his departure.

Ueno had informed the Navy Ministry about the costs before signing, but Kawamura's response to postpone the order for the armored frigate did not arrive until 8 October.

Six cylindrical boilers provided steam to the engine at a working pressure of 4.22 bar (422 kPa; 61 psi).

They carried a maximum of 345–390 long tons (351–396 t) of coal,[6] enough to steam 3,100 nautical miles (5,700 km; 3,600 mi) at 10 knots (19 km/h; 12 mph).

[11] During the 1880s, the armament of the Kongō-class ships was reinforced with the addition of four quadruple-barreled 25-millimeter (1.0 in) Nordenfelt and two quintuple-barreled 11-millimeter (0.4 in) Nordenfeldt machine guns for defense against torpedo boats.

Hiei and Kongō ferried the 69 survivors of the wrecked Ertuğrul back to Turkey where the ships' officers were received by Sultan Abdul Hamid II.

[18] Until the end of the century, one or the other of the Kongō-class ships made the annual cadet cruise, usually to countries bordering the Pacific Ocean.