Brazilian battleship Riachuelo (1914)

Project 781
History
Brazil
Name	Riachuelo
Namesake	Battle of Riachuelo
Builder	Armstrong Whitworth
Laid down	10 September 1914 (planned)
Fate	Construction cancelled
General characteristics
Displacement	30,500 tonnes (30,000 long tons; 33,600 short tons)
Length	188.98 metres (620.0 ft)
Beam	28.65 metres (94.0 ft)
Draft	8.53 metres (28.0 ft)
Propulsion	2 steam turbine sets
Speed	23 knots (43 km/h)
Armament	(as planned) 4 × twin 15 in (381 mm) guns 14 × 6 in (152 mm) guns 3 × 3 in (76.2 mm) AA guns 2 × torpedo tubes
Armor	Belt: 13.5 in (342 mm)

Riachuelo was a battleship project for the Brazilian Navy developed between 1913 and 1914. It was designed to be the most powerful warship of its time; it was a Brazilian response to the Chilean projects Almirante Latorre and Almirante Cochrane and to the Argentine projects Rivadavia and Moreno, during the naval arms race in South America. The construction would be carried out by the British construction company Armstrong Whitworth and Vickers, under the codename Project 781, a project chosen among several other plans offered to the Brazilian authorities. The battleship would be 188.98 meters long and have at least eight 381-millimeter guns, displacing up to 30,500 nautical tons.

Due to the outbreak of World War I, construction was delayed. Although the contract for construction was signed on 14 May 1914, by November of that year little work had been done at the shipyard. Construction was officially canceled on 13 May 1915. The Brazilian Naval League tried to keep the construction alive by financing it through a national donation campaign, but the amount of funds raised was not sufficient to cover the costs. If finished, Riachuelo would have been compared to the British Revenge and Queen Elizabeth classes.