of the ships' sides. It was thickest over the boiler and engine rooms, ranging from thick. Their magazines were protected by an additional of HTS. There was a 1-inch aft transverse bulkhead of mild steel and the conning tower was protected by 3-inch HTS plates. The ships' deck protection consisted of 1- to 1.5-inch HTS. Cavendish as an aircraft carrier In January 1917, the Admiralty reviewed the navy's aircraft carrier requirements and decided to order two ships fitted with a flying-off deck as well as a landing deck aft. The initial order had to be cancelled in April 1917 for lack of building facilities, so the Admiralty decided to convert Cavendish, already under construction, in June 1917. She was renamed Vindictive to perpetuate the name of the cruiser sunk at the Second Ostend Raid and her construction was rushed to bring her into service before her cruiser sisters. The forward superfiring 7.5-inch gun, two 3-inch guns and the conning tower were removed and the forward superstructure was remodelled into a hangar with a capacity for six reconnaissance aircraft. The hangar roof, with a small extension, formed the flying-off deck. The aircraft were hoisted up through a hatch at the aft end of the flying-off deck by two derricks. The landing deck required the removal of the aft superfiring pair of 7.5-inch guns and moving the four 3-inch AA guns to an elevated platform between the funnels, in lieu of the 3-inch guns intended for that position. A port side gangway wide connected the landing and flying-off decks to allow aircraft with their wings folded to be wheeled from one to the other. A crash barrier was hung from "the gallows" at the forward end of the landing on deck. To increase her stability after the addition of so much topweight, the upper portion of her anti-torpedo bulge was enlarged. She completed her sea trials on 21 September 1918 and reached a speed of from . Modifications The earliest modification related to the secondary armament. The low-angle guns were all gone by 1921, leaving Hawkins with only her four 12-pounder anti-aircraft (A/A) guns, while Raleigh seems to have obtained two QF 4-inch Mark V guns in their stead. The first major refit to the class came in 1923, when Vindictive was converted back into a cruiser configuration - but the hangar beneath her bridge was retained, and in place of 'B'