The ''Pará''-class monitors were a group of six wooden-hulled

ironclad An ironclad was a steam engine, steam-propelled warship protected by iron armour, steel or iron armor constructed from 1859 to the early 1890s. The ironclad was developed as a result of the vulnerability of wooden warships to explosive or ince ...

monitors Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, West ...

named after Brazilian provinces and built in Brazil for the

Imperial Brazilian Navy The Imperial Brazilian Navy (Brazilian Portuguese: ''Armada Nacional'', commonly known as ''Armada Imperial'') was the navy created at the time of the independence of the Empire of Brazil from the United Kingdom of Portugal, Brazil and the Algar ...

during the

Paraguayan War The Paraguayan War (, , ), also known as the War of the Triple Alliance (, , ), was a South American war that lasted from 1864 to 1870. It was fought between Paraguay and the Triple Alliance of Argentina, the Empire of Brazil, and Uruguay. It wa ...

in the late 1860s. The first three ships finished, , and , participated in the

Passage of Humaitá The Passage of Humaitá (Portuguese language, Portuguese: ''Passagem de Humaitá'') was an operation of riverine warfare during the Paraguayan War − the most lethal in South American history − in which a force of six Imperial Brazilian Navy ...

in February 1868. Afterwards the remaining ships joined the first three and they all provided fire support for the army for the rest of the war. The ships were split between the newly formed Upper Uruguay () and

Mato Grosso Mato Grosso ( – ) is one of the states of Brazil, the List of Brazilian states by area, third largest by area, located in the Central-West Region, Brazil, Central-West region. The state has 1.66% of the Brazilian population and is responsible ...

Flotilla A flotilla (from Spanish, meaning a small ''flota'' ( fleet) of ships), or naval flotilla, is a formation of small warships that may be part of a larger fleet. Composition A flotilla is usually composed of a homogeneous group of the same cla ...

s after the war. ''Alagoas'' was transferred to

Rio de Janeiro Rio de Janeiro, or simply Rio, is the capital of the Rio de Janeiro (state), state of Rio de Janeiro. It is the List of cities in Brazil by population, second-most-populous city in Brazil (after São Paulo) and the Largest cities in the America ...

in the 1890s and participated in the Fleet Revolt of 1893–94.

Design and description

The ''Pará''-class

river monitor River monitors are military craft designed to patrol rivers. They are normally the largest of all riverine warships in river flotillas, and mount the heaviest weapons. The name originated from the US Navy's , which made her first appearance in ...

s were designed to meet the need of the Brazilian Navy for small, shallow-draft armored ships capable of withstanding heavy fire during the

, which saw

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

and Brazil allied against

Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...

. The two foreign-built river monitors already in service drew enough water that they could not operate on the shallower rivers in Paraguay. The monitor configuration was chosen as a turreted design did not have the same problems engaging enemy ships and fortifications as did the

casemate ironclad The casemate ironclad was a type of iron or iron-armored gunboat briefly used in the American Civil War by both the Confederate States Navy and the Union Navy. Unlike a monitor-type ironclad which carried its armament encased in a separate ...

s already in Brazilian service. The

oblong An oblong is an object longer than it is wide, especially a non-square rectangle. Oblong may also refer to: Places * Oblong, Illinois, a village in the United States * Oblong Township, Crawford County, Illinois, United States * A strip of land ...

gun turret A gun turret (or simply turret) is a mounting platform from which weapons can be fired that affords protection, visibility and ability to turn and aim. A modern gun turret is generally a rotatable weapon mount that houses the crew or mechanis ...

sat on a circular platform that had a central pivot. It was rotated by four men via a system of gears; 2.25 minutes were required for a full 360° rotation. A bronze

ram Ram, ram, or RAM most commonly refers to: * A male sheep * Random-access memory, computer memory * Ram Trucks, US, since 2009 ** List of vehicles named Dodge Ram, trucks and vans ** Ram Pickup, produced by Ram Trucks Ram, ram, or RAM may also ref ...

was fitted to these ships as well. The hull was sheathed with

Muntz metal Muntz metal (also known as yellow metal) is an alpha-beta brass alloy composed of approximately 60% copper, 40% zinc and a trace of iron. It is named after George Fredrick Muntz, a metal-roller of Birmingham, England, who commercialised the al ...

to reduce

biofouling Biofouling or biological fouling is the accumulation of microorganisms, plants, algae, or small animals where it is not wanted on surfaces such as ship and submarine hulls, devices such as water inlets, pipework, grates, ponds, and rivers that ...

.Gratz, p. 153 The ships measured long overall, with a beam of . They had a

draft Draft, the draft, or draught may refer to: Watercraft dimensions * Draft (hull), the distance from waterline to keel of a vessel * Draft (sail), degree of curvature in a sail * Air draft, distance from waterline to the highest point on a v ...

between of and displaced . With only of freeboard they had to be towed between Rio de Janeiro and their area of operations. Their crew numbered 43 officers and men.Gratz, p. 154

Propulsion

The ''Pará''-class ships had two direct-acting

steam engines A steam engine is a heat engine that performs Work (physics), mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a Cylinder (locomotive), cyl ...

, each driving a single propeller. Their engines were powered by two tubular

boiler A boiler is a closed vessel in which fluid (generally water) is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, centra ...

s at a working pressure of . The engines produced a total of which gave the monitors a maximum speed of in calm waters. The ships carried enough coal for one day's steaming.

Armament

The first three ships carried a single 70-pounder Whitworth rifled muzzle loader (RML) in their gun turret, but the last three ships substituted a 120-pounder Whitworth RML. The 70-pdr gun had a maximum elevation of 15°, but the larger gun's elevation was reduced because of its longer barrel. Both guns had a similar maximum range of . The 70-pdr gun weighed and fired a shell that weighed . The shell of the 120-pdr gun weighed while the gun itself weighed . Most unusually the guns' Brazilian-designed iron

carriage A carriage is a two- or four-wheeled horse-drawn vehicle for passengers. In Europe they were a common mode of transport for the wealthy during the Roman Empire, and then again from around 1600 until they were replaced by the motor car around 1 ...

was designed to pivot vertically at the muzzle; this was done to minimize the size of the gunport through which splinters and shells could enter.

Armor

The hull of the ''Pará''-class ships was made from three layers of wood that alternated in orientation. It was thick and was capped with a layer of peroba hardwood. The ships had a complete

wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.05%) in contrast to that of cast iron (2.1% to 4.5%), or 0.25 for low carbon "mild" steel. Wrought iron is manufactured by heating and melting high carbon cast iron in an ...

waterline belt, high. It had a maximum thickness of 102 millimeters amidships, decreasing to and at the ship's ends. The curved deck was armored with of wrought iron. The gun turret was shaped like a

rectangle In Euclidean geometry, Euclidean plane geometry, a rectangle is a Rectilinear polygon, rectilinear convex polygon or a quadrilateral with four right angles. It can also be defined as: an equiangular quadrilateral, since equiangular means that a ...

with rounded corners. It was built much like the hull, but the front of the turret was protected by of armor, the sides by 102 millimeters and the rear by 76 millimeters. Its roof and the exposed portions of the platform it rested upon were protected by 12.7 millimeters of armor. The armored

pilothouse A bridge (also known as a command deck), or wheelhouse (also known as a pilothouse), is a room or platform of a ship, submarine, airship, or spacecraft, spaceship from which the ship can be commanded. When a ship is under way, the bridge is manne ...

was positioned ahead of the turret.

Construction

Service history

The first three ships finished, ''Pará'', ''Alagoas'' and ''Rio Grande'', participated in the

on 19 February 1868. For the engagement the three river monitors were lashed to the larger ironclads in case any engines were disabled by the Paraguayan guns. led with ''Rio Grande'', followed by with ''Alagoas'' and with ''Pará''. Both ''Alagoas'', which had taken an estimated 200 hits, and ''Pará'' had to be beached after passing the fortress to prevent them from sinking. ''Alagoas'' was under repair at São José do Cerrito until mid-March, although ''Pará'' joined a squadron to capture the town of Laureles on 27 February. ''Rio Grande'' continued upstream with the other undamaged ships and they bombarded

Asunción Asunción (, ) is the capital and the largest city of Paraguay. The city stands on the eastern bank of the Paraguay River, almost at the confluence of this river with the Pilcomayo River. The Paraguay River and the Bay of Asunción in the north ...

on 24 February with little effect. On 23 March ''Rio Grande'' and ''Barroso'' sank the Parguayan steamer ''Igurey'' and both ships were boarded by Paraguayan soldiers on the evening of 9 July, although they managed to repel the boarders.Gratz, pp. 149–150, 157 For the rest of the war the river monitors bombarded Paraguayan positions and

artillery batteries In military organizations, an artillery battery is a unit or multiple systems of artillery, mortar systems, rocket artillery, multiple rocket launchers, surface-to-surface missiles, ballistic missiles, cruise missiles, etc., so grouped to fac ...

in support of the army, notably at Angostura, Timbó and along the Tebicuary and

Manduvirá River The Manduvirá River (Spanish: ''Río Manduvirá''; Guarani: ''Ysyry Manduvira'') is a river of Paraguay. It is a tributary of the Paraguay River The Paraguay River (''Ysyry Paraguái'' in Guarani language, Guarani, ''Rio Paraguai'' in Portugues ...

s. After the war the ships were divided between the newly formed Upper Uruguay and Mato Grosso Flotillas. ''Alagoas'' was transferred to Rio de Janeiro in the 1890s and participated in the Fleet Revolt of 1893–1894. The ships were disposed of during the last two decades of the 19th century, although ''Rio Grande'' was docked for reconstruction in 1899. The work was never completed and she was eventually scrapped in 1907.Gratz, p. 157

Notes

References

* * *

External links

Alphabetical listing of Brazilian warships
{{DEFAULTSORT:Para-class monitor Ships built in Brazil Monitor classes Riverine warfare