Following the outbreak of World War I in August 1914, Gaulois escorted troop convoys from French North Africa to France for a month and a half.

She was en route to the Dardanelles after a refit in France when she was torpedoed and sunk on 27 December by a German submarine; four crewmen were lost.

[3] These boilers were coal-burning with auxiliary oil sprayers and were designed to produce 14,200 metric horsepower (10,444 kW; 14,006 ihp) to give the Charlemagne class a speed of 17 knots (31 km/h; 20 mph).

[4] During her sea trials, Gaulois reached a top speed of 18 knots (33 km/h; 21 mph) from 14,220 metric horsepower (10,459 kW; 14,025 ihp).

[2] The Charlemagnes carried their main battery of four Canon de 305 mm (12 in) Modèle 1893 guns in two twin-gun turrets, one each fore and aft of the superstructure.

[7] Gaulois, named after the tribes that inhabited France during Roman times,[8] was ordered on 22 January 1895 from the Arsenal de Brest.

The following month, while exercising in the harbour at Hyères, Gaulois accidentally rammed the destroyer Hallebarde, gouging a 4-by-1.5-metre (13.1 by 4.9 ft) hole in the smaller ship.

On 18 July, after combined manoeuvres with the Northern Squadron, the ship participated in a naval review conducted by the President of France, Émile Loubet, at Cherbourg.

The following year, Gaulois and the Mediterranean Squadron participated in an international naval review by Loubet in Toulon with ships from Spain, Italy and Russia.

[10] In October 1901, the 1st Battleship Division, under the command of Rear-Admiral (contre-amiral) Leonce Caillard, was ordered to proceed to the port of Mytilene on the island of Lesbos, then owned by the Ottoman Empire.

In May 1902, the ship became the flagship of Vice-Admiral (vice-amiral) François Fournier who led a small delegation to celebrate the unveiling of the statue of Comte de Rochambeau in Lafayette Square, Washington, D.C. On 23 May President Theodore Roosevelt was received aboard and the ship visited New York City and Boston before heading back to France.

Together with the battleships Iéna and Bouvet, the ship aided survivors of the April 1906 eruption of Mount Vesuvius in Naples, Italy.

In June 1914, the Navy planned to assign Gaulois to the Training Division of the Squadron as of October, but this was cancelled upon the outbreak of war in August.

[15] Together with the older French pre-dreadnoughts, the ship's first mission in the war was to escort troop convoys from North Africa to France.

Gaulois was ordered to Tenedos Island, not far from the Ottoman Gallipoli Peninsula, in November to guard against a sortie by the ex-German battlecruiser Yavuz Sultan Selim, relieving the battleship Suffren which needed a refit in Toulon.

During the subsequent bombardment on 25 February, the ship anchored some 6,000 metres (6,600 yd) from the Asiatic shore and engaged the forts at Kum Kale and Cape Helles.

Five days later, the French squadron attempted to suppress the Ottoman guns defending the Dardanelles while British battleships bombarded the fortifications.

Little could be done to staunch the inflow and Captain André-Casimir Biard decided to head for the Rabbit Islands, north of Tenedos, where he could beach his ship for temporary repairs.

He ordered the non-essential crewmen off the ship in case she foundered en route, but managed to reach the islands, escorted by Charlemagne.

The ship anchored 1,000 metres (1,100 yd) off the shore on 11 August to bombard an Ottoman artillery battery at Achi Baba.

[21] By 27 December, Gaulois had reached the Sea of Crete and was off the southern coast of Greece when she was torpedoed by the German submarine UB-47 at 08:03 despite being escorted by the destroyer Dard and two armed trawlers.