The Town-class destroyers were a group of 50 destroyers of the Royal Navy and the Royal Canadian Navy that were in service during the Second World War. They were transferred from the United States Navy in exchange for military bases in the British West Indies and Newfoundland, as outlined in the Destroyers for Bases Agreement between the United Kingdom and United States, signed on 2 September 1940. They were known as "four-pipers" or "four-stackers" because they had four smokestacks (funnels). Later classes of destroyers typically had one or two.

Some went to the Royal Canadian Navy at the outset. Others went on to the Royal Norwegian Navy, the Royal Netherlands Navy, and the Soviet Navy after serving with the Royal Navy. Although given a set of names by the Commonwealth navies that suggested they were one class they actually came from three classes of destroyer: Caldwell, Wickes, and Clemson. "Town class" refers to the Admiralty's practice of renaming these ships after towns common to the United States and the British Commonwealth.^[3] Ships initially commissioned into the Royal Canadian Navy, however, followed the Canadian practice of giving destroyers the names of Canadian rivers. The rivers selected for the Town class were on the border between Canada and the United States, with the exception of Annapolis — the name of both a river in Annapolis County, Nova Scotia, and the location of the United States Naval Academy.^[4]

One of the Town-class ships achieved lasting fame: HMS Campbeltown (ex-USS Buchanan). In the Commando raid Operation Chariot, Campbeltown, fitted with a large demolition charge, rammed the gates of the Normandie dock at Saint-Nazaire, France. The charge detonated on 29 March 1942, breaching the drydock and destroying Campbeltown, thus destroying the only drydock on the Atlantic coast capable of accepting the Tirpitz. This exploit was depicted in the 1950 Trevor Howard film The Gift Horse, which starred HMS Leamington (ex-USS Twiggs) after her return from service in the Soviet Union.

Built for service during the First World War, but in the main completed after the end of that conflict, the flush-deckers were, by 1940, the oldest destroyers in the US Navy, and many had been mothballed for the inter-war period. While contemporaneous to the British V and W-class destroyers they were not much liked by their crews. While the V and W classes set a new standard for destroyer design, the flush-deckers were already obsolescent by comparison.^[5] They were uncomfortable and wet, working badly in a seaway. Their hull lines were rather narrow and 'herring-gutted' which gave them a vicious roll. The officers didn't like the way they handled either, since they had been built with propellers that turned the same way (2-screw ships normally have the shafts turning in opposite directions as the direction of rotation has effects on the rudder and the whole ship when manoeuvring, especially when coming alongside), so these were as awkward to handle as single-screw ships. Their turning circle was enormous, as big as most Royal Navy battleships, making them difficult to use in a submarine hunt which demanded tight manoeuvres, compounded by unreliable "chain and cog" steering gear laid across the main deck. They also had fully enclosed bridges which caused problems with reflections in the glass at night. One Royal Canadian Navy corvette captain described them as "the most dubious gift since the Trojan Horse".^[6] However, despite their disadvantages they were a welcome addition to forces escorting convoys in the Atlantic at a time when the U-boats, operating from newly acquired bases on the Atlantic coast of France were becoming an increasingly serious threat to British shipping. They were also seen as an earnest of the United States’ commitment to support Britain against Nazism.^[7]

The original armament was four 4-inch (102 mm) guns,^[8] one 3-inch (76 mm) anti-aircraft gun, and twelve torpedo tubes.^[9] On the Wickes-class, the 4-inch gun placement was one gun in a shield on the forecastle, one on the quarterdeck and one each side on a platform between the number 2 and number 3 funnels. The Admiralty promptly removed one of the 4-inch guns and six torpedo tubes to improve stability.^[10] Twenty-three of the class had further armament reductions for anti-submarine escort of trade convoys.^[11] Two of the remaining 4-inch guns and three of the remaining torpedo tubes were removed to allow increased depth charge stowage and installation of Hedgehog anti-submarine mortar system.^[11]

The ships were divided by the Royal Navy into four groups based on their characteristics.^[12]

• Type A corresponded to the 20 ships of the Clemson class, having a standard displacement of 1,190 tons powered by geared turbines that produced a maximum speed of 28.5 knots. They were armed with four single 4-inch guns and one 3-inch anti-aircraft gun, with triple 21-inch torpedo tubes. Overall length was 314 ft 4 in, beam 31 ft 8 in and draught 12 ft 10 in.
• Type B were the 12 ships of the Wickes class built to plans prepared by the Bath Iron Works. These were lighter than the type A ships, with a displacement of 1090 tons but they had the same armament and machinery with a slightly better speed of 28.75 kt.
• Type C were the 15 ships of the Wickes class built to plans prepared by Bethlehem Steel, with a displacement of 1,060 tons and an improved speed of 29.75 kt.
• Type D were the 3 ships of the Caldwell class, smaller again at 1020 tons, with a gun armament of four single 3-inch guns and built with direct drive turbines, but having a speed of 30 kt. The type D vessels were recognizable also in having only three funnels.