In naval terminology, a destroyer is a fast, maneuverable, long-endurance warship intended to escort larger vessels in a fleet, convoy, or carrier battle group and defend them against a wide range of general threats. They were originally conceived in 1885 by Fernando Villaamil for the Spanish Navy as a defense against torpedo boats, and by the time of the Russo-Japanese War in 1904, these "torpedo boat destroyers" (TBDs) were "large, swift, and powerfully armed torpedo boats designed to destroy other torpedo boats". Although the term "destroyer" had been used interchangeably with "TBD" and "torpedo boat destroyer" by navies since 1892, the term "torpedo boat destroyer" had been generally shortened to simply "destroyer" by nearly all navies by the First World War.
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.
A river gunboat is a type of gunboat adapted for river operations. River gunboats required shallow draft for river navigation. They would be armed with relatively small caliber cannons, or a mix of cannons and machine guns. If they carried more than one cannon, one might be a howitzer, for shore bombardment. They were usually not armoured. The fictional USS San Pablo described in Richard McKenna's The Sand Pebbles is an example of this class of vessel, serving on the US Navy's Yangtze Patrol. Stronger river warships with larger guns were river monitors.
Twelve ships and two shore establishments of the Royal Navy have been named HMS Defiance. Others have borne the name whilst serving as depot ships and tenders to the establishments:
The Amethyst incident, also known as the Yangtze incident, was a historic event which involved the Royal Navy ships HMS Amethyst, HMS Consort, HMS London, and HMS Black Swan on the Yangtze River for three months during the Chinese Civil War in the summer of 1949.
The Yangtze Patrol, also known as the Yangtze River Patrol Force, Yangtze River Patrol, YangPat and ComYangPat, was a prolonged naval operation from 1854 to 1949 to protect American interests in the Yangtze River's treaty ports. The Yangtze Patrol also patrolled the coastal waters of China where they protected U.S. citizens, their property, and Christian missionaries.
HMS Searcher was a Ruler-class escort carrier of the Royal Navy. Built in Seattle as a Bogue-class, she was transferred to the United Kingdom under Lend-Lease. Launched in 1942 she served until 29 November 1945. She was sold into merchant service and renamed Captain Theo. In 1966, she was renamed again to Oriental Banker and was finally scrapped in Taiwan in 1976.
The Nanking Incident occurred in March 1927 during the capture of Nanjing by the National Revolutionary Army (NRA) in their Northern Expedition. Foreign warships bombarded the city to defend foreign residents against rioting and looting. Several ships were involved in the engagement, including vessels of the Royal Navy and the United States Navy. Marines and sailors were also landed for rescue operations including some 140 Dutch forces. Both Nationalist and Communist soldiers within the NRA participated in the rioting and looting of foreign-owned property in Nanjing.
HMS Trincomalee is a Royal Navy Leda-class sailing frigate built shortly after the end of the Napoleonic Wars. She is now restored as a museum ship afloat in the National Museum of the Royal Navy, Hartlepool, England.
The Insect-class gunboats were a class of small but well-armed Royal Navy ships designed for use in shallow rivers or inshore. They were intended for use on the Danube against Austria-Hungary. The first four ships—Gnat, Mantis, Moth and Tarantula—were first employed during the Mesopotamian Campaign of the First World War on the Euphrates and Tigris rivers.
HMS Sparrowhawk was a B-class torpedo boat destroyer of the Royal Navy. She was completed by Laird, Son & Company, Birkenhead, and was launched on 8 October 1895. She served on the China Station and was wrecked in the mouth of the Yangtze River in 1904. She was one of four Quail-class destroyers.
Toba (鳥羽) was a river gunboat of the Imperial Japanese Navy, part of the 11th Gunboat Sentai, that operated on the Yangtze River in China during the 1930s, and during the Second Sino-Japanese War and World War II.
Coastal Forces was a division of the Royal Navy initially established during World War I, and then again in World War II under the command of Rear-Admiral, Coastal Forces. It remained active until the last minesweepers to wear the "HM Coastal Forces" cap tally were taken out of reserve in 1968. The division received more gallantry awards than any other branch of the Royal Navy during that period.
HMS Peterel was a river gunboat built by Yarrow Shipbuilders at Scotstoun and she was the sixth ship of the Royal Navy to carry the name. Her name used an archaic spelling for consistency with previous Royal Navy Ships of the same name, in contrast to the modern accepted spelling petrel.
Twenty-two ships of the Royal Navy have borne the name HMS Falcon. They are named after an exceptionally fast bird of prey.
HMS Cockchafer was a Royal Navy Insect-class gunboat. She was built by Barclay Curle and launched on 17 December 1915 as the fifth Royal Navy ship to carry this name. The Insect class was originally designed for service on the River Danube but most of them spent much of their service on Chinese rivers.
The Seta-class gunboats were a class of four riverine gunboats of the Imperial Japanese Navy. They entered service in 1923 for use along the Yangtze River in China. The remained in service through the Second Sino-Japanese War and World War II. Three of the gunboats were damaged beyond repair and broken up during World War II. The fourth, Seta, was surrendered at the end of the war, and taken over by the Republic of China Navy and renamed Chang Teh. During the Chinese Civil War, Chang Teh was captured by Communist Chinese forces.
The Yongfeng class were early-20th century gunboats built for the Chinese navy. They were enlarged sea-going versions of the Kiang- and Chu-class gunboats. The first ships, Yongfeng and Yongxiang, were built in Japan by Kawasaki; they were launched in 1912-1913. The remainder, Yongjian and Yongji, were built in 1915 by the Jiangnan Shipyard in China; these ships had added poop decks.
HMS Gannet was a river gunboat of the Royal Navy built by Yarrow Shipbuilders in 1927 for Yangtze Patrol. Gannet is the sister ship of HMS Peterel.
Ermanno Carlotto was a river gunboat of the Italian Regia Marina. After the Italian armistice of 1943 she served in the Imperial Japanese Navy as Narumi, while after the end of World War II she was used by the Navy of the Republic of China and then by the Navy of the People's Republic of China as Qian Kun.
United Kingdom 
Nationalist China 
Communist China 