ARA Rosario, date unknown
Class overview
Name	Rosario class riverine gunboat
Builders	Armstrong, Mitchell & Co., Newcastle-on-Tyne, North East England
Operators	Argentine Navy
Built	1908–1909
In service	1909–1951
In commission	1909–1959
Planned	2
Completed	2
Retired	2
General characteristics
Type	Rosario class gunboat
Displacement	709 (standard) to 1055 (full load) tons
Length	76.4 m (250.7 ft)
Beam	9.8 m (32.2 ft)
Draft	4.3 m (14 ft)
Propulsion	2-shaft, 2 × Vickers triple-expansion steam engines, 2 x Yarrow boilers, 1,300 ihp (970 kW), 160 tons coal
Speed	14.5 knots (16.7 mph; 26.9 km/h)
Range	1000 nautical miles @ 8 kn
Complement	145
Armament	2 × 152-millimetre (6 in) howitzers 6 × 76-millimetre (3 in) guns 4 × 7.65 mm (0.301 in) machine guns
Armour	hull belt, deck and conning tower ( see text)
Notes	Specifications from “Conway’s All the World’s Fighting Ships, 1906–1921”.

The Rosario-class gunboats were a class of two pre-World War I warships, designed and built in England in 1907–1909 as armoured riverine gunboats, to patrol the rivers Paraná and Uruguay. They were in service with the Argentine Navy from the late 1900s to the early 1950s. The lead ship of the class was named after Rosario, one of the major cities in Argentina.^{[citation needed]}

Argentina decided the construction of new warships due to the deterioration of relations with Brazil, who was after the naval supremacy in South America. The Brazilian Navy ordered riverine monitors to patrol the border rivers; Argentina's response was to place a contract with the British shipyard Armstrong, Mitchell & Co for the construction of two riverine gunboats.^[1]

The Rosario class gunboats had a shallow draft metal hull with a single mast and funnel on the superstructure amidships. They had an armoured belt of 4-inch (102 mm) thick Krupp cemented armour, an armoured deck 1-inch (25 mm) thick, and armoured conning tower. They were powered by two Vickers triple-expansion steam engines fed by two Yarrow boilers, driving two propellers.^[2][3]

Its main battery was composed of two 152-millimetre (6 in) howitzers and six 76-millimetre (3 in) guns. The secondary battery was composed of two 37 mm Nordenfelt autocannons and 4 to 8 7.65 mm (0.301 in) machine guns. It also carried two 75-millimetre (3 in) naval landing guns with wheeled carriage.^[2][3]

The Rosario class was designed in the mid 1900s and the ships were laid down in 1907 and completed in 1908–1909. They were commissioned by the Argentine Navy in 1908–1909 and remained in service until the early 1950s.^[2][3]

Rosario and Paraná were frequently used to patrol the rivers Paraná and Uruguay; and were deployed to Asunción during the 1911 revolution in Paraguay. They were also used in training exercises, and occasionally deployed to Patagonia.^[2][3]

Both ships were sold for scrap after being decommissioned,^[2][3] and were broken up in the 1960s.^{[citation needed]}

• List of ships of the Argentine Navy
• Javary-class monitor – riverine monitor ordered but never commissioned by Brazil

• Arguindeguy, Pablo (1972). Apuntes sobre los buques de la Armada Argentina (1810–1970) (in Spanish). Buenos Aires, Argentina: Comando en Jefe de la Armada.
• Brook, Peter (1999). Warships for Export: Armstrong Warships 1867–1927. Gravesend, UK: World Ship Society. ISBN 0-905617-89-4.
• Gardiner, Robert & Gray, Randal (1985). Conway's All The World's Fighting Ships 1906–1921. London: Conway Maritime Press. p. 439. ISBN 0-85177-245-5.

• Burzio, Humberto (1960). Armada Nacional (in Spanish). Secretaria de Estado de Marina.

• "Cañonera "Rosario" - 1909". Historia y Arqueologia Marítima (in Spanish). Retrieved 2016-12-17.
• "River gunboat "Rosario"". Tyne Built Ships. Retrieved 2016-12-17.
• "River gunboat "Paraná"". Tyne Built Ships. Retrieved 2016-12-17.