They spent most of the rest of the war blockading the Straits of Otranto and the Dardanelles to prevent warships of the Central Powers from breaking out into the Mediterranean.

One ship ran aground and the crew of the other mutinied after one of its members was killed during a protest against intervention in support of the Whites.

The only survivor still afloat at the beginning of World War II in August 1939 had been hulked in 1931 and was serving as part of the navy's torpedo school.

The Danton-class ships were ordered as the second tranche of a French naval expansion plan that began in response to the growth of the Imperial German Navy after 1900.

One proposal was made to replace the 240-millimeter guns turrets with single 305-millimeter (12 in) turrets to create an "all-big-gun" ship, like the British battleship HMS Dreadnought, but this was rejected as it would have raised the displacement above the 18,000-metric ton limit and the slower-firing 305-millimeter guns would have reduced the volume and weight of fire to an unacceptable degree.

[2] Initial parliamentary discussion of the design focused less on the anticipated cost of the ships than the idea that France was being left behind in the technological arms race, particularly in regard to the innovative Parsons steam turbines used by HMS Dreadnought.

To further complicate things, Thomson requested a study using the heavier and more powerful 45-caliber 305-millimeter Modèle 1906 gun on 3 August while not endorsing the navy's decision to use turbines.

Thomson was inclined to accept Dudebout's recommendation, but prevaricated until December, after parliamentary debates showed overwhelming support for turbines in all six ships.

He sent another technical mission to Britain to look at Babcock & Wilcox's design in April 1907, but did not make a decision in favor of French-built boilers until 3 June 1908, after all the ships had been laid down.

The turbines were rated at a total of 22,500 shaft horsepower (16,800 kW) using steam provided by the boilers at a working pressure of 18 kg/cm2 (1,765 kPa; 256 psi).

The Dantons carried a maximum of 2,027 tonnes (1,995 long tons) of coal which gave them an estimated range from 3,120–4,866 nautical miles (5,778–9,012 km; 3,590–5,600 mi) at a speed of 12 knots (22 km/h; 14 mph), depending on which boilers were fitted.

Their endurance was almost half that of their predecessors due to the uneconomical fuel consumption of their turbines at low speeds and meant that they needed frequent coaling stops during the war.

[7] The main battery of the Danton-class ships consisted of four 305 mm Modèle 1906 guns mounted in two twin-gun turrets, one each fore and aft of the superstructure.

The Dantons also had storage space for 10 Harlé Modèle 1906 mines, which had an explosive charge of 60 kilograms (130 lb) of guncotton.

Integrating these into the overall fire-control system took some time, so eight Ponthus & Therrode stadimeters, which required knowledge of the target's mast height and overall length, were used in the interim.

[11] The main gun turrets had 340 millimeters (13.4 in) of armor on their faces, 260-millimeter (10 in) sides, and roofs of three layers of 24-millimeter (0.94 in) mild-steel plates.

The walls of its communication tube down to the fire-control center (poste central de tir) were 200 millimeters thick down to the upper protected deck.

Inboard of the bulkhead were 16 watertight compartments, 12 of which were normally kept empty, but the 4 abreast the boiler rooms were used as coal bunkers.

Construction was prolonged by a number of factors, chief of which were the 500 plus changes were made to the original design and in the inability of Thomson to make a timely decision.

For example, water in the lower end of the newly completed Point-du-Jour slip at Brest meant that building Danton's stern was delayed four months after the bow began and construction of Mirabeau could not begin until the armored cruiser Waldeck-Rousseau was launched.

[22] When the war began, the squadron, under the command of Vice Admiral Paul Chocheprat, was at sea preparing to escort troop convoys from French North Africa to France.

Later that month, all of the ships, except Mirabeau, participated in the Battle of Antivari in the Adriatic Sea and helped to sink an Austro-Hungarian protected cruiser.

They spent most of the rest of the war blockading the Straits of Otranto and the Dardanelles to prevent German, Austro-Hungarian and Turkish warships from breaking out.

[22] Diderot, Mirabeau and Vergniaud briefly participated in the occupation of Constantinople after the end of the war and the latter two ships were sent to the Black Sea in early 1919 during the Southern Russia Intervention.