Even before the fighting of World War 2 (1939-1945) broke out, the British Royal Navy was keen on the threat posed by aircraft on their many ships. These aerial threats could fly farther and faster than their progenitors of the previous World War and so there was attention given to reworking old, outgoing cruisers to serve as floating air defense platforms while an all-new initiative was also undertaken - this produced the sixteen-strong "Dido-class" light cruisers outfitted with appropriate air defense armament. The warships could therefore be used in defending itself, critical fleet elements or important offshore air space as needed through a combined battery of cannons and machine guns.
HMS Dido (37) became the lead ship of this new class and saw her keel laid down on October 26th, 1937 by shipbuilder Cammell Laird of Birkenhead, UK. The vessel was launched on July 18th, 1939 and commissioned on September 30th, 1940. World War 2 formally began on September 1st, 1939 with the German invasion of Poland, prompting the war declaration to come from the British Government. As it stood, Britain and its Royal Navy had been at war with the Axis for over a year by the time HMS Dido was ready for action - her services desperately needed.
HMS Dido displaced 5,600 tons (long) under standard load and 6,850 tons (long) under full load. She featured a length of 512 feet, a beam of 50.5 feet, and a draught of 14 feet. Power was served from 4 x Admiralty 3-drum oil-fired boilers feeding 4 x Parsons geared steam turbines driving 4 x shafts through an output of 62,000 horsepower. Maximum speed in ideal conditions was just over 32 knots with a range out to 4,880 miles when cruising at 16 knots.
Her profile was well-balanced yet traditional in most respects, her center dominated by a section of open space between the twin smoke funnels. The forward superstructure was large and held the collection of bridge, communications, and sensor components that were the true nerve center of the warship. Her crew complement could number between 480 to 535 personnel and armor protection included 76mm at the belt, 25mm along the deck, 51mm at the magazines and 25mm at the bulkheads. Two masts were seated flanking midships and a five-turret-approach made up her main battery. No second battery was installed for this specialist ship.
As finalized, the main battery consisted of 10 x 5.25" (133mm) Dual-Purpose (DP) lightweight guns set across five twin-gunned turrets - three held fore and two aft. These guns were originally designed for the King George-class battleships of 1939 - sixteen such guns were installed on these massive warships. A single 4" (102mm) Anti-Aircraft (AA) gun and 12 x 2-pounder "pom-pom" cannons (in three four-gunned turrets) served in the local defense role. The last "line of defense" became 8 x 0.50 caliber (13mm) heavy machine guns fitted as two quadruple-gunned turrets. The vessel also carried 6 x 530mm (21") torpedo tubes, a common practice for surface warships of the period.
Of the sixteen vessels in the class, the final five (making up the "Bellona Group") were completed with eight 5.25" DP guns and also featured reinforced mast works and lower-profile smoke funnels.
Once in action HMS Dido gave good service as a protector ship - accompanying convoys, defending the skies for Allied ships against attack aircraft, and laying her guns down on inland targets. She served primarily in the Mediterranean theater where the threat of the Italian Navy loomed large in the early going. In September of 1940, she was outfitted with Type 281 radar for improved situational awareness. From the span of 1941 to 1943, her armament featured 5 x 20mm Oerlikon AA guns in lieu of the original 102mm and 0.50 caliber fittings. She suffered a severe bomb hit at her stern and landed at Massawa (Eritrea) for repairs in August of 1942. With repairs completed as best as possible (in a short six days), the vessel was sent back into service. Her guns were used in offshore bombardment of enemy positions against Gaeta, Lazio on the Italian western coast during the Allied drive to Rome. By 1945, the warship had added five additional 20mm AA guns to improve her air defense prowess. Throughout the whole of the war - which HMS Dido managed to survive - the class lost five of her sixteen in the fighting.
While a good fighting platform on the whole, HMS Dido and her class were eventually limited by their armament fitting - the 5.25" main battery was deemed too light for bombardment of inland targets or engagement of steel-clad warships of the period yet too slow-firing for engaging fast-moving enemy aircraft. Nevertheless any warship was better than none and the class was used as efficiently as possible through to the end of the conflict in 1945.
In one of her last gestures as a fighting warship, HMS Dido served as flagship of the reserve fleet during the Queen's coronation in 1953. With the vessel's services no longer needed in post-war Britain, she was stripped of her useful parts and sold off for scrap on July 18th, 1957. Much of the class met the same fate by the end of the decade.
HMS Diadem (Bellona Group) served with the Pakistani Navy from 1956 on and was finally relieved in 1985.