The belt ranged in thickness from . Because of manufacturing limitations, the thinner end plates were nickel steel. Behind the belt was a cofferdam, backed by a longitudinal watertight bulkhead. The upper armored deck met the top of the belt and had a total thickness of while the lower armored deck curved down to meet the bottom of the belt and had a uniform thickness of . The main-gun turrets were protected by of Harvey armor, but their barbettes used plates of ordinary steel. The face and sides of the secondary turrets were thick and the plates protecting their barbettes were thick. The casemates protecting the 100-millimeter guns also had a thickness of 102 millimeters. The face and sides of the conning tower were 174 millimeters thick. "Sully", named after the statesman Maximilien de Béthune, Duke of Sully, was authorized in the 1898 Naval Program and was ordered from Forges et Chantiers de la Méditerranée on 24 May 1899. The ship was laid down on that same day at their shipyard in La Seyne-sur-Mer, launched on 4 June 1901, and completed in June 1904. The ship was sent to French Indochina for her first commission. On 7 February 1905 "Sully" struck a rock in Hạ Long Bay; her crew was not injured. Her guns and equipment were salvaged, but the ship broke in two and was abandoned as a total loss.