Designed by the naval architectEmile Bertin, the Gueydon-class ships were intended to be smaller and cheaper than the preceding armored cruiserdesign,. Like the older ship, they were intended to fill the commerce-raiding strategy of the Jeune École. The ships measured long overall with a beam of and had a maximum draft of. They displaced. They had a crew of 566 officers and enlisted men. The Gueydon class had three vertical triple-expansion steam engines, each driving a single propeller shaft. Steam for the engines was provided by 20 or 28 boilers and they were rated at a total of that gave them a speed of. The ships carried up to of coal and could steam for at a speed of. The ships of the Gueydon class had a main armament that consisted of two 40-caliber Canon de 194 mm Modèle 1893-1896| guns that were mounted in single gun turrets, one each fore and aft of the superstructure. Their secondary armament comprised eight 45-caliber quick-firing Canon de 164 mm Modèle 1893| guns in casemates. For anti-torpedo boat defense, they carried four 45-caliber QF Canon de 100 mm Modèle 1891| guns on the forecastle deck, ten QF QF 3-pounder Hotchkiss| and four QF Hotchkiss guns. They were also armed with two submerged torpedo tubes. The Harvey armor belt of the Gueydon-class cruisers extended from below the waterline to the main deck. It reached the upper deck for a length of from the bow and covered the entire length of the ship except for of the stern where it ended in a transverse bulkhead thick. The lower strake of armor was generally thick, although it reduced to forward, aft, and thinned to at its lower edge. The upper strake of armor had thicknesses of and between the main and upper decks. The curved lower protective deck ranged in thickness from 2 to 2.2 inches. In addition there was a light armor deck thick at the top of the lower armor strake. A watertight internal cofferdam, filled with cellulose, stretched between these two decks. The gun turrets were protected by armor and had roofs thick. Their ammunition hoists had 2 inches of armor and the 100-millimeter guns were protected by gun shields. The sides of the conning tower were 160 millimeters thick. The forward end of the casemate compartment was closed off by a bulkhead and a bulkhead extended down to the lower deck at the rear end of the compartment.
Ships
Dupetit-Thouars was torpedoed and sunk in 1918.
Gueydon was decommissioned in 1935 and used as accommodation at Brest, was bombed and sunk in 1944, with the wreck broken up in 1945/46.
Montcalm was decommissioned in 1926 and used as accommodation at Brest, renamed Tremintin in 1934, was bombed and sunk in 1944, with the wreck broken up in 1946/47.
