Like many late pre-dreadnought designs, Démocratie was completed after the revolutionary British battleship HMS Dreadnought had entered service, rendering her obsolescent.

She immediately began the normal peacetime training routine of squadron and fleet maneuvers and cruises to various ports in the Mediterranean.

[2] Démocratie's main battery consisted of four 305 mm (12 in) Modèle 1893/96 guns mounted in two twin-gun turrets, one forward and one aft of the superstructure.

The secondary battery consisted of ten 194 mm (7.6 in) Modèle 1902 guns; six were mounted in single turrets, and four in casemates in the hull.

Also in 1915, the 47 mm guns located on either side of the bridge were removed and the two on the aft superstructure were moved to the roof of the rear turret.

[5] Following her completion, she left Brest on 20 January and steamed south to Toulon, where she joined the 1st Division of the 1st Battle Squadron on 10 March, which included the battleships Patrie and République.

After his departure, the Mediterranean Squadron conducted training exercises off Corsica, followed by a naval review in Villefranche for President Armand Fallières on 26 April.

The ships then steamed north to La Pallice, where they conducted tests with their wireless telegraphy sets and shooting training in Quiberon Bay.

[7] Démocratie joined Patrie, Justice, Vérité, République, and Suffren for a simulated attack on the port of Nice on 18 February.

Démocratie and the rest of 1st Squadron and the armored cruisers Ernest Renan and Léon Gambetta went on a cruise in the western Mediterranean in May and June, visiting a number of ports including Cagliari, Bizerte, Bône, Philippeville, Algiers, and Bougie.

Admiral Augustin Boué de Lapeyrère inspected both battleship squadrons in Golfe-Juan from 2 to 12 July, after which the ships cruised first to Corsica and then to Algeria.

The 2nd Squadron departed Toulon on 23 August with the armored cruisers Jules Ferry and Edgar Quinet and two destroyer flotillas to conduct training exercises in the Atlantic.

While en route to Brest, the ships stopped in Tangier, Royan, Le Verdon, La Pallice, Quiberon Bay, and Cherbourg.

Accordingly, Démocratie and the rest of the 2nd Squadron were sent to Algiers, where they joined a group of seven passenger ships that had a contingent of 7,000 troops from XIX Corps aboard.

In the ensuing Battle of Antivari, Boué de Lapeyrère initially ordered his battleships to fire warning shots, but this caused confusion among the fleet's gunners that allowed Ulan to escape.

[17] The French fleet patrolled the southern end of the Adriatic for the next three days with the expectation that the Austro-Hungarians would counterattack, but their opponent never arrived.

[18][19][20] The fleet continued these operations in October and November, including a sweep off the coast of Montenegro to cover a group of merchant vessels replenishing their coal there.

The patrols continued through late December, when an Austro-Hungarian U-boat torpedoed Jean Bart, leading to the decision by the French naval command to withdraw the main battle fleet from direct operations in the Adriatic.

[21][22] Démocratie and Justice were detached from the main fleet in January 1916 to reinforce the Dardanelles Division, though the Allies evacuated their forces fighting there that month.

Démocratie left on 11 April for repairs in Toulon and collided with the Russian steamer SS Odessa off Cape Maleas, though she was not significantly damaged.

In June, the French battle fleet was reorganized; Démocratie, her two sisters, the two République-class ships, and Suffren were assigned to the 3rd Squadron.

The ships were tasked with pressuring the Greek government, which to that point had remained neutral, since King Constantine I's wife Sophie was the sister of the German Kaiser Wilhelm II.

The French and British were growing increasingly frustrated by Constantine's refusal to enter the war, and sent the 3rd Squadron to try to influence events in the country.

Over the course of June and July, the ships alternated between Salonika and Mudros, and the squadron was transferred to Corfu on 12 August, where it joined the rest of the French fleet.

Several French ships sent men ashore in Athens on 1 December to support the coup, but they were quickly defeated by the royalist Greek Army.

In late October, members of the Central Powers began signing armistices with the British and French, signaling the end of the war.

[24][25] Shortly after the end of the war, Démocratie, Justice, and a destroyer joined an Allied fleet (including the British dreadnoughts HMS Superb and Temeraire and the Italian pre-dreadnought Roma) that was sent to the Black Sea port of Sevastopol.

The latter vessel then returned to Constantinople where she joined the 2nd Squadron, which at that time also included Justice, the Danton-class ships Diderot and Vergniaud, and the dreadnought France.