main deck was thick in two layers on the flat that increased to on the slopes that connected it to the main belt. The second deck was thick, also in two layers. Fore and aft transverse bulkheads connected the armored belt to the decks. The frontal armor of the gun turrets was in thickness with thick sides, and an roof and rear. Their barbettes also had 230-millimeter armor above the forecastle deck that reduced to between the forecastle and upper decks and 130 millimeters below the upper deck. The forward conning tower had walls 280 millimeters thick; those of the aft conning tower were 180 millimeters thick. The total weight of the protective armor was , just over 25 per cent of the ships' designed displacement. The total weight of the entire protective system was , 30.2 per cent of their intended displacement. Modifications and reconstruction Shortly after the end of World War I, the number of 50-caliber 76 mm guns was reduced to 13, all mounted on the turret tops, and six new 40-caliber 76-millimeter anti-aircraft (AA) guns were installed abreast the aft funnel. In addition two license-built 2-pounder AA guns were mounted on the forecastle deck abreast 'B' turret. In 1925–1926 the foremast was replaced by a tetrapodal mast, which was moved forward of the funnels, the rangefinders were upgraded, and the ships were equipped to handle a Macchi M.18 seaplane mounted on the center turret. Around that same time, one or both of the ships was equipped with a fixed aircraft catapult on the port side of the forecastle. The sisters began an extensive reconstruction program directed by Vice Admiral (Generale del Genio navale) Francesco Rotundi in October 1933. This lasted until June 1937 for Conte di Cavour and October 1937 for Giulio Cesare, and resulted in several changes. A new bow section was grafted over the existing bow which increased their length by to and their beam increased to . Their draft at deep load increased to for Conte di Cavour and for Giulio Cesare. All of the changes made during their reconstruction increased their displacement to at standard load and at deep load. The ships' crews increased to 1,260 officers and enlisted men. Only 40% of the original ship's structure remained after the reconstruction was completed. Two of the propeller shafts were removed and the existing turbines were replaced by two Belluzzo geared steam turbines