A gunboat is a naval watercraft designed for the express purpose of carrying one or more guns to bombard coastal targets, as opposed to those military craft designed for naval warfare, or for ferrying troops or supplies.
In the age of sail, a gunboat was usually a small undecked vessel carrying a single smoothbore cannon in the bow, or just two or three such cannons. A gunboat could carry one or two masts or be oar-powered only, but the single-masted version of about 15 m (49 ft) length was most typical. Some types of gunboat carried two cannons, or else mounted a number of swivel guns on the railings.
The advantages of this type of gunboat were that since it only carried a single cannon, that cannon could be quite heavy—for instance, a 32-pounder—and that the boat could be maneuvered in shallow or restricted waters, where sailing was difficult for larger ships. A single hit from a frigate would demolish a gunboat, but a frigate facing six gunboats in an estuary would likely be seriously damaged before it could manage to sink all of them. Gunboats were also easy and quick to build; the combatants in the 1776 Battle of Valcour Island on Lake Champlain in New York were mostly gunboats built on the spot.
All navies of the sailing era kept a number of gunboats on hand. Gunboats saw extensive use in the Baltic Sea during the late 18th century as they were well-suited for the extensive coastal skerries and archipelagoes of Sweden, Finland and Russia. The rivalry between Sweden and Russia in particular lead to an intense expansion of gunboat fleets and development of new gunboat types. The two clashed during the Russo-Swedish war of 1788-90 a conflict that culminated in the massive Battle of Svensksund in 1790, where over 30,000 men and hundreds of gunboats, galleys and other oared craft participated. The majority of these were vessels developed from the 1770s and onwards by the naval architect Fredrik Henrik af Chapman for the Swedish Archipelago Fleet. The designs were copied and refined by the rival Danish and Russian navies and spread to the Mediterranean and the Black Sea.
Two variants were the most common, a larger 20 m (66 ft) "gun sloop" (from the Swedish kanonslup) with two 24-pounders, one in the stern and one in the bow, and a smaller 15 m (49 ft) "gun yawl" (kanonjolle) with a single 24-pounder. Many of the Baltic navies kept gunboats in service well into the second half of the 19th century. British ships engaged larger 22 m (72 ft) Russian gunboats off Turku in southeast Finland in 1854 during the Crimean War. The Russian vessels had the distinction of being the last oared vessels of war in history to fire their guns in anger.
Gunboats were a key part of Napoleon's plan for the invasion of England in 1804. Denmark-Norway used them heavily in the Gunboat War. Between 1803 and 1812, the United States Navy had a policy of basing its navy on coastal gunboats. It experimented with a variety of designs, but they were nearly useless in the War of 1812, and went back to being special-purpose vessels.
Steam era 
With the introduction of steam power in the early 19th century, the Royal Navy and other navies built considerable numbers of small vessels propelled by side paddles and later by screws. Initially, these vessels retained full sailing rigs, so that steam propulsion was used as an auxiliary form.
The British Royal Navy deployed two wooden paddle gunboats in the Lower Great Lakes and St. Lawrence River during the Rebellions of 1837 in Upper and Lower Canada. The United States Navy deployed an iron-hulled paddle gunboat, the USS Michigan, to the Great Lakes in 1844.
The Von der Tann was the first propeller-driven gunboat in the world. Conradi shipyards in Kiel built the steam-powered 120 long tons (120 t) gunboat in 1849 at for the small navy of Schleswig-Holstein. Initially called "Gunboat No. 1", Von der Tann was the most modern ship in the navy. She participated successfully in the First Schleswig War.
Britain built a large number of wooden screw gunboats during the 1850s, some of which participated in the Crimean war, Second Opium War and Indian Mutiny. The requirement for gunboats in the Crimean war was formulated in 1854 and was to allow for shore bombardment operations to be carried out in the Baltic. The first ships the Royal Navy built that met this requirement were the Arrow-class gunvessels. Then in mid-1854 the Royal Navy ordered six Gleaner-class gunboats followed latter in the year by an order for 20 Dapper-class gunboats. In May 1855, six Dapper-class gunboats were deployed to the Sea of Azov where they repeatedly raided and destroyed stores around its coast. In June 1855, the Royal Navy reentered the Baltic with a total of 18 gunboats as part of a larger fleet. The boats were used to attack various coastal facilities operating alongside larger warships from which they drew supplies such as coal.
Gunboats experienced a revival during the American Civil War. Armed sidewheel steamers were quickly converted from existing passenger-carrying boats by Union and Confederate forces. Later, some boats were purposely built, such as the USS Miami. They all frequently mounted 12 or more guns, sometimes of rather large caliber, and were usually armored to some degree. At the same time, Britain's gunboats from the Crimean war period were starting to wear out so a new series of classes was ordered. At the same time, construction shifted from a purely wooden hull to an iron teak composite.
In the later 19th century and early 20th century, "gunboat" was the common name for smaller armed vessels, often called "patrol gunboats"[by whom?]. These could be classified, from the smallest to the largest, into river gunboats, river monitors, coastal defense gunboats (such as the SMS Panther), and full-fledged monitors for coastal bombardments. In the 1870s-1880s, Britain took to building so called "flat-iron" (or Rendel) gunboats for coastal defence. When there would be few opportunities to re-coal, vessels carrying a full sailing rig were still used as gunboats; HMS Gannet, a sloop preserved at Chatham Historic Dockyard in the United Kingdom, is an example of this type of gunboat.
In the U.S. Navy, these boats had the hull classification symbol "PG"; they usually displaced under 2,000 long tons (2,000 t), were about 200 ft (61 m) long, 10–15 ft (3.0–4.6 m) draught and sometimes much less, and mounted several guns of caliber up to 5–6 in (130–150 mm). An important characteristic of these was the ability to operate in rivers, enabling them to reach inland targets in a way not otherwise possible before the development of aircraft. In this period, gunboats were used by the naval powers for police actions in colonies or weaker countries, for example in China (see e.g. Yangtze Patrol). It is this category of gunboat that inspired the term "gunboat diplomacy". With the addition of torpedoes they became "torpedo gunboats".
In Britain, much of the gunboat fleet was disposed of as part of Admiral Fisher's reforms in the 1900s. A handful were still in service in various roles at the start of World War I. The very last in active service were two of the second Bramble class which survived until 1926 carrying out river patrols in west Africa.
In the circumstances of World War I, however, the Royal Navy re-equipped with small (625 long tons (635 t)), shallow draught gunboats (12 ships of the Insect class) with sufficient speed to operate in fast-flowing rivers and relatively heavy armament. During the War and in the post-war period, these were deployed in Romania on the Danube, in Mesopotamia on the Euphrates and Tigris, in northern Russia on the Northern Dvina and in China on the Yangtze. In China, during anarchic and war conditions, they continued to be deployed until World War II in defence of British interests; other western Powers did the same.
More, larger, gunboats were built in the late 1930s for the Far East. Some were sailed there; others were transported in sections and reassembled at Shanghai.
World War II and the United Kingdom 
Most British gunboats were withdrawn from the Far East early in World War II and redeployed in the Indian Ocean and the Mediterranean, where they supported various army operations in north Africa and southern Europe. Those that remained in the Far East were either handed over to the Chinese (HMS Sandpiper, renamed Ying Hao) or lost to the Japanese.
Vietnam War 
U.S. riverine gunboats in the Vietnam War, utilized Patrol Boats River (PBR), which were constructed of fiberglass; Patrol Craft Fast (PCF), commonly known as Swift Boats, which were built of aluminum; and Assault Support Patrol Boats (ASPB) built of steel. U.S. Coast Guard 82-foot Point class cutters supplemented these U.S. Navy vessels. The ASPBs were commonly referred to as "Alpha" boats and were primarily deployed for mine sweeping duties along the water ways, due to their all steel construction. The ASPB's were the only U.S. Navy riverine craft specifically designed and built for the Vietnam War. All of these boats were assigned to the U.S. Navy's "Brownwater Navy".
See also 
- Alarm class torpedo gunboat
- Dryad class torpedo gunboat
- Insect class gunboat
- Japanese gunboat Chiyodagata
- Japanese gunboat Seta
- Japanese gunboat Unyo
- List of gunboat and gunvessel classes of the Royal Navy
- SMS Panther
- HMS Rattlesnake (1886)
- Monitor (warship)
- Redbreast class gunboat
- River gunboat
- River monitor
- Russian gunboat Korietz
- Soviet gunboat Krasnoye Znamya
- Spanish gunboat Callao
- Spanish gunboat General Concha
- Spanish gunboat Marques del Duero
- Torpedo gunboat
- HMS Vixen (1865)
- Von der Tann (gunboat)
- Yorktown class gunboat
- See Glete (1993), pp. 710-11 for lists of European navies that employed rowed gunboats
- Anderson (1962), pp. 97-99
- Anderson (1962), p.98.
- Preston (2007), pp. 19–22
- Preston (2007), pp. 26–27
- Preston (2007), p. 28
- Preston (2007), pp. 68–69
- Preston (2007), pp. 162–163
- Preston (2007), pp. 122–124
- Preston (2007), pp. 128–129
- Preston (2007), pp. 131
- Friedman (1987)
- Historic Naval Ships Visitors Guide, "Escort and Patrol Vessels"
Print references 
- Anderson, Roger Charles, Oared Fighting Ships: From classical times to the coming of steam. London. 1962.
- Chapelle, Howard, The History of the American Sailing Navy Norton. 1949.
- Friedman, Norman. US Small Combatants: An Illustrated Design History. 1987; Naval Institute Press. ISBN 0-87021-713-5.
- Glete, Jan, Navies and Nations: Warships, Navies and State Building in Europe and America 1500-1860 (vol 2) Almqvist & Wiksell International, Stockholm. 1993. ISBN 91-22-01565-5
- Preston, John Antony, Send a Gunboat! The Victorian Navy and Supremacy at Sea, 1854-1904. Conway Maritime, London. 2007. ISBN 978-0-85177-923-2.
Web references