Question: Temes-class river monitor was a type of warship that was first used in what decade?

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SMS Leitha: SMS "Leitha" or Lajta Monitor Museumship was the first river monitor in Europe and the oldest and also the only remaining, fully restored warship of the Austro-Hungarian Navy.

Canopy goanna: The canopy goanna ("Varanus keithhornei") is a species of monitor lizards native to northeast Australia.  It is also known as the blue-nosed tree monitor, Keith Horne's monitor, or occasionally as the Nesbit River monitor It belongs to the subgenus "Euprepiosaurus" and is a member of the "Varanus prasinus" species group.

Yugoslav monitor Sava: The Yugoslav monitor "Sava was a "Temes"-class river monitor built for the Austro-Hungarian Navy as SMS "Bodrog.  She fired the first shots of World War I on the night of 28 July 1914, when she and two other monitors shelled Serbian defences near Belgrade.  She was part of the Danube Flotilla, and fought the Serbian and Romanian armies from Belgrade to the mouth of the Danube.  In the closing stages of the war, she was the last monitor to withdraw towards Budapest, but was captured by the Serbs when she grounded on a sandbank downstream from Belgrade.  After the war, she was transferred to the newly created Kingdom of Serbs, Croats and Slovenes (later Yugoslavia), and renamed "Sava".  She remained in service throughout the interwar period, although budget restrictions meant she was not always in full commission.

USS Monitor: USS "Monitor" was an iron-hulled steamship.  Built during the American Civil War, she was the first ironclad warship commissioned by the Union Navy.  "Monitor" is most famous for her central role in the Battle of Hampton Roads on 9 March 1862, where, under the command of Lieutenant John Worden, she fought the casemate ironclad  (built on the hull of the former steam frigate USS "Merrimack" ) to a standstill.  The unique design of the ship, distinguished by its revolving turret which was designed by American inventor Theodore Timby, was quickly duplicated and established the monitor type of warship.

Monitor (warship): A monitor was a relatively small warship which was neither fast nor strongly armoured but carried disproportionately large guns.  They were used by some navies from the 1860s, during the First World War and with limited use in the Second World War.  During the Vietnam War they were used by the United States Navy.  The Brazilian Navy's "Parnaíba" is the last monitor in service.

President Masaryk (monitor): The President Masaryk was a river monitor of the First Czechoslovak Republic, serving from 1932 until the dissolution of the republic in 1939.  With four 66 mm guns in two twin turrets, it was that nation's most powerful warship of the 1930s and flagship of the Czechoslovakian river flotilla.  After the German occupation, the ship was taken into the German army under the name Bechelaren and fought against the Soviets.  It was scrapped in 1978.

Yugoslav monitor Drava: The Yugoslav monitor "Drava was a river monitor operated by the Royal Yugoslav Navy between 1921 and 1941.  She was originally built for the Austro-Hungarian Navy as the name ship of the "Enns"-class river monitors.  As SMS "Enns, she was part of the Danube Flotilla during World War I, and fought against the Serbian and Romanian armies from Belgrade to the lower Danube.  In October 1915, she was covering an amphibious assault on Belgrade when she was holed below the waterline by a direct hit, and had to be towed to Budapest for repairs.  After brief service with the Hungarian People's Republic at the end of the war, she was transferred to the newly created Kingdom of Serbs, Croats and Slovenes (later Yugoslavia), and renamed "Drava".  She remained in service throughout the interwar period, but was not always in full commission due to budget restrictions.

List of monitors of World War II: A monitor is a class of relatively small warship that is lightly armoured, often provided with disproportionately large guns, and originally designed for coastal warfare.  The term "monitor" grew to include breastwork monitors, the largest class of riverine warcraft known as river monitors, and was sometimes used as a generic term for any turreted ship.  In the early 20th century, the term "monitor" included shallow-draft armoured shore bombardment vessels, particularly those of the Royal Navy: the "Lord Clive"-class monitor s carried guns that fired the heaviest shells ever used at sea and saw action against German targets during World War I.  Two small Royal Navy monitors from the First World War, "Erebus" and "Terror" survived to fight in the Second World War.  When the requirement for shore support and strong shallow-water coastal defence returned, new monitors and variants such as coastal defence ships were built (e.g. the British "Roberts"-class monitor s).  Allied monitors saw service in the Mediterranean in support of the British Eighth Army's desert and Italian campaigns.  They were part of the offshore bombardment for the Invasion of Normandy in 1944.  They were also used to clear the German-mined River Scheldt by the British to utilize the port of Antwerp.  The German, Yugoslav, Croatian, Romanian, Hungarian and Czech armed forces operated river monitors that saw combat during World War II.

NMS Mihail Kogălniceanu: NMS "Mihail Kogălniceanu" was a monitor of the Romanian Navy.  She saw service in both world wars, being the most successful vessel in her class of four ships.  Like her three sisters, she was initially built as a river monitor, but in early 1918, she was converted to a sea-going monitor.

Temes-class river monitor: The Temes class was a class of originally Austro-Hungarian river monitor warships used during World War I.

Supporting paragraphs: Temes-class river monitor Monitor (warship)
Answer: 1860s