The Town-class destroyers were a group of destroyers transferred from the United States Navy to the Royal Navy and the Royal Canadian Navy in exchange for military bases in the Bahamas and elsewhere, as outlined in the Destroyers for Bases Agreement between Britain 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.