The Italian Castore class gunboats, Castore and Polluce, were a class of two Rendel gunboats

Flat-iron gunboat

Flat-iron gunboats were a number of classes of coastal gunboats generally characterised by small size, low freeboard and the absence of masts.Some Rendel-type gunboats were fitted with masts ; they are included in the article for...

, designed and built by Sir W G Armstrong Mitchell & Co.

Armstrong Whitworth

Sir W G Armstrong Whitworth & Co Ltd was a major British manufacturing company of the early years of the 20th century. Headquartered in Elswick, Newcastle upon Tyne, Armstrong Whitworth engaged in the construction of armaments, ships, locomotives, automobiles, and aircraft.-History:In 1847,...

's Elswick Works

Elswick, Tyne and Wear

Elswick is a ward of the city of Newcastle upon Tyne, England, in the western part of the city, bordering the river Tyne. One of the earliest references to the coal mining industry of the north east occurs in 1330, when it was recorded that the Prior of Tynemouth let a colliery, called Heygrove, at...

 in the late 1880s to a contract by the Italian War Ministry. Designed by Philip Watts

Philip Watts (naval architect)

Sir Philip Watts, KCB FRS was a British naval architect, famous for his design of the revolutionary Elswick cruiser and the HMS Dreadnought.-Early life:...

 and Herbert Rowell, and constructed in Elswick's Tyneside

River Tyne

The River Tyne is a river in North East England in Great Britain. It is formed by the confluence of two rivers: the North Tyne and the South Tyne. These two rivers converge at Warden Rock near Hexham in Northumberland at a place dubbed 'The Meeting of the Waters'.The North Tyne rises on the...

 yard in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, the two gunboats were dissassembled and shipped to Italy for reassembly in the Armstrong facility at Pozzuoli

Pozzuoli

Pozzuoli is a city and comune of the province of Naples, in the Italian region of Campania. It is the main city of the Phlegrean peninsula.-History:Pozzuoli began as the Greek colony of Dicaearchia...

, proving to be the only ships constructed there after the Italian government cancelled the shipyard project. It is uncertain whether the vessels were designed as testbeds for heavy guns, or were intended from the outset as operational gunboats.

Design

Both vessels were laid down in the Elswick yard on 22 February 1887. Built to a design calling for a length of 115 feet (35.1 m) and a beam of 37 feet (11.3 m), giving them a length to beam ratio of 3.1:1, they displaced 667 long tons (677.7 t) under normal conditions, and were powered by two steam engines, driving a pair of propellers that gave a speed of around 8 knots (15.7 km/h).

As constructed, both vessels were armed with a single, massive Krupp

Krupp

The Krupp family , a prominent 400-year-old German dynasty from Essen, have become famous for their steel production and for their manufacture of ammunition and armaments. The family business, known as Friedrich Krupp AG Hoesch-Krupp, was the largest company in Europe at the beginning of the 20th...

 40 centimetres (16 in), 32-caliber

Caliber

In guns including firearms, caliber or calibre is the approximate internal diameter of the barrel in relation to the diameter of the projectile used in it....

 cannon mounted on the stern, that could be elevated to an angle of 13 degrees

Degree (angle)

A degree , usually denoted by ° , is a measurement of plane angle, representing 1⁄360 of a full rotation; one degree is equivalent to π/180 radians...

, firing a 1980 pounds (898.1 kg) shell.

Castore

Castore was launched in September 1888, and conducted her trials in 1889 at Pozzuoli. She had her heavy gun removed in 1889, and was commissioned into the Italian Navy on 18 July 1891 as a gunboat. Rearmed with a single 12 centimetres (4.7 in) gun, she served until 1899 when she was disarmed and reclassified as a barge. In 1904, she was reclassifed again as a minelayer, and served in that role until late 1915 when she was designated as a torpedo testing craft. After serving in this role throughout the First World War, she was stricken and discarded on 8 October 1925.

Polluce

Polluce was launched in October 1888, and conducted her trials in 1889 at Pozzuoli. She was commissioned into the Italian Navy on 18 July 1891 along with her sister vessel, but retained her heavy gun until 1899, when she was rearmed with a single 12 cm (4.7 in) gun. She saw no action in her time serving the Regia Marina, and in 1911, she was stricken and discarded.