After the signing of the London Treaty, a discussion started about small naval cruisers. In 1936, a project featuring five rapid-firing 134 mm twin mounts was presented. HMS Dido, the lead ship of the series, entered service in September 1940. At the beginning of World War II, she escorted convoys in the Atlantic and then relocated to the Mediterranean. The cruiser participated in the second battle in the Gulf of Sirte in 1942, in the landings in Sicily in 1943, and served off the south coast of France in 1944. In 1945, she escorted Arctic convoys and supported strikes off the coast of Norway.