Although upgraded several times before World War II, she was not considered to be a first-line battleship by the 1930s and spent much of that decade as a gunnery training ship.

As part of Operation Catapult, the ship was seized in Portsmouth by British forces on 3 July and was turned over to the Free French a week later.

By 1909, the French Navy was convinced of the superiority of the all-big-gun battleship like HMS Dreadnought over mixed-calibre designs such as the Danton class, which preceded the Courbets.

The following year, the new Minister of the Navy, Augustin Boué de Lapeyrère, selected a design that was comparable to the foreign dreadnoughts then under construction to be built as part of the 1906 Naval Programme.

[5] The Courbet-class ships carried enough coal and fuel oil to give them a range of 4,200 nautical miles (7,800 km; 4,800 mi) at a speed of 10 knots (19 km/h; 12 mph).

[10] By the time that France declared war on Germany on 2 August, Courbet had been relieved of her assignment to the 1st Division because Boué de Lapeyrère had become commander of the 1st Naval Army and the ship was now the fleet flagship.

Since the whereabouts of the German battlecruiser SMS Goeben was unknown, he split his forces into three groups to cover the movements of troop convoys between French North Africa and metropolitan France.

He accompanied the 2nd Battle Squadron (Group B) to Bougie, French Algeria, in Courbet before rendezvousing with her sisters Jean Bart and France off Valencia, Spain, to escort them to Toulon because the guns of the former were malfunctioning and the latter was so new that she did not have any ammunition aboard.

[11] When France declared war on Austria-Hungary on 12 August, Boué de Lapeyrère decided on a sortie into the Adriatic intended to force the Austro-Hungarian fleet to give battle.

On 1 September, the 1st Naval Army briefly bombarded Austro-Hungarian coastal fortifications defending the Bay of Cattaro to discharge the unfired shells remaining in the guns after sinking Zenta.

[13] The torpedoing of Jean Bart on 21 December by the Austro-Hungarian submarine U-12 showed that the battleships were vulnerable to this threat, and they were withdrawn to spend the rest of the month further south at an anchorage in Navarino Bay.

[14] On 11 January 1915, the French were alerted that the Austro-Hungarian fleet was going to sortie from its base at Pola, so Courbet, Paris and France led the Naval Army north to the Albanian coast.

At the beginning of 1917, the French began to use the Greek island of Corfu as well, but shortages of coal severely limited the battleships' ability to go to sea.

At some point during the year, Courbet's mainmast was shortened and a motorised winch was installed to allow her to operate a kite balloon, but this was not a success.

[15] After the war ended on 11 November, Courbet returned to Toulon for a refit; the ship was briefly placed in reserve before she became Vice-Admiral Charlier's flagship between 6 June 1919 and 20 October 1920.

[16] The following year, she became a gunnery training ship at Toulon,[4] but she suffered a serious boiler fire on 6 June 1923 that required repairs, so she was given the first of her modernisations between 9 July 1923 and 16 April 1924, at La Seyne-sur-Mer.

[17] Courbet and the battleship Provence visited Naples, Italy, on 15–19 June 1925 then rendezvoused with Jean Bart and Paris at Mers-el-Kebir, French Algeria, for manoeuvres in the Bay of Biscay with the Atlantic-based ships that began on the 26th.

They were mobilised on 21 May with augmented crews and assigned to the command of Vice-Admiral Jean-Marie Abrial for the defence of the French ports on the English Channel.

[21] Courbet provided gunfire support to the defenders of Cherbourg on 19 June against the advancing 7th Panzer Division and then covered the evacuation of the town by the Allies during Operation Aerial.

[22] The ship had to be towed from Weymouth on 7 June by a pair of British tugboats as her engines and boilers had been removed earlier and replaced with concrete.