World War II: Attack on Mers el Kebir

Battleship Bretagne
Battleship Bretagne explodes during Operation Catapult. Wikimedia Commons

The attack on the French fleet at Mers el Kebir took place on July 3, 1940, during World War II (1939-1945).

Events Leading up to the Attack

During the closing days of the Battle of France in 1940, and with the German victory all but assured, the British became increasingly worried about the disposition of the French fleet. The fourth largest navy in the world, the ships of the Marine Nationale possessed the potential to alter the naval war and threaten Britain's supply lines across the Atlantic. Voicing these concerns to the French government, Prime Minister Winston Churchill was assured by Navy Minister Admiral François Darlan that even in defeat, the fleet would be kept from the Germans.

Unknown to either side was that Hitler had little interest in taking over the Marine Nationale, only ensuring that its ships were neutralized or interned “under German or Italian supervision.” This latter phrase was included in Article 8 of the Franco-German armistice. Misinterpreting the language of the document, the British believed that the Germans intended to take control of the French fleet. Based on this and a distrust of Hitler, the British War Cabinet decided on June 24 that any assurances provided under Article 8 should be disregarded.

Fleets and Commanders During the Attack


  • Admiral Sir James Somerville
  • 2 battleships, 1 battlecruiser, 2 light cruisers, 1 aircraft carrier, & 11 destroyers


  • Admiral Marcel-Bruno Gensoul
  • 2 battleships, 2 battlecruisers, 6 destroyers, & 1 seaplane tender

Operation Catapult

At this point in time, the ships of the Marine Nationale were scattered in various ports. Two battleships, four cruisers, eight destroyers, and numerous smaller vessels were in Britain, while one battleship, four cruisers, and three destroyers were in port at Alexandria, Egypt. The largest concentration was anchored at Mers el Kebir and Oran, Algeria. This force, led by Admiral Marcel-Bruno Gensoul, consisted of the older battleships Bretagne and Provence, the new battlecruisers Dunkerque and Strasbourg, the seaplane tender Commandant Teste, as well as six destroyers.

Moving forward with plans to neutralize the French fleet, the Royal Navy began Operation Catapult. This saw the boarding and capture of French ships in British ports on the night of July 3. While the French crews generally did not resist, three were killed on the submarine Surcouf. The bulk of the ships went on to serve with Free French forces later in the war. Of the French crews, the men were given the option to join the Free French or be repatriated across the Channel. With these ships seized, ultimatums were issued to the squadrons at Mers el Kebir and Alexandria.

Ultimatum at Mers el Kebir

To deal with Gensoul's squadron, Churchill dispatched Force H from Gibraltar under the command of Admiral Sir James Somerville. He was instructed issue an ultimatum to Gensoul requesting that the French squadron do one of the following:

  • Join the Royal Navy in continuing the war with Germany
  • Sail to a British port with reduced crews to be interned for the duration
  • Sail to the West Indies or the United States and remain there for the rest of the war
  • Scuttle their ships within six hoursIf Gensoul refused all four options, Somerville was instructed to destroy the French ships to prevent their capture by the Germans.

A reluctant participant who did not wish to attack an ally, Somerville approached Mers el Kebir with a force consisting of the battlecruiser HMS Hood, the battleships HMS Valiant and HMS Resolution, the carrier HMS Ark Royal, two light cruisers, and 11 destroyers. On July 3, Somerville sent Captain Cedric Holland of Ark Royal, who spoke fluent French, into Mers el Kebir aboard the destroyer HMS Foxhound to present the terms to Gensoul. Holland was coldly received as Gensoul expected negotiations to be conducted by an officer of equal rank. As result, he sent his flag lieutenant, Bernard Dufay, to meet with Holland.

Under orders to present the ultimatum directly to Gensoul, Holland was refused access and ordered to leave the harbor. Boarding a whaleboat for Foxhound, he made a successful dash to the French flagship, Dunkerque, and after additional delays were finally able to meet with the French admiral. Negotiations continued for two hours during which Gensoul ordered his ships to prepare for action. Tensions were further heightened as Ark Royal's aircraft began dropping magnetic mines across the harbor channel as talks progressed.

A Failure of Communication

During the course of the talks, Gensoul shared his orders from Darlan which permitted him to scuttle the fleet or sail for America if a foreign power attempted to claim his ships. In a massive failure of communication, the full text of Somerville's ultimatum was not relayed to Darlan, including the option of sailing for the United States. As talks began to stalemate, Churchill was becoming increasingly impatient in London. Concerned that the French were stalling to allow reinforcements to arrive, he ordered Somerville to settle the matter at once.

An Unfortunate Attack

Responding to Churchill's orders, Somerville radioed Gensoul at 5:26 PM that if one of the British proposals was not accepted within fifteen minutes he would attack. With this message Holland departed. Unwilling to negotiate under threat of enemy fire, Gensoul did not respond. Approaching the harbor, the ships of Force H opened fire at an extreme range approximately thirty minutes later. Despite the approximate similarity between the two forces, the French were not fully prepared for battle and anchored in a narrow harbor. The heavy British guns quickly found their targets with Dunkerque put out of action within four minutes. Bretagne was struck in a magazine and exploded, killing 977 of its crew. When the firing stopped, Bretagne had sunk, while Dunkerque, Provence, and the destroyer Mogador were damaged and run aground.

Only Strasbourg and a few destroyers succeeded in escaping the harbor. Fleeing at flank speed, they were ineffectively attacked by Ark Royal's aircraft and briefly pursued by Force H. The French ships were able to reach Toulon the next day. Concerned that the damage to Dunkerque and Provence was minor, British aircraft attacked Mers el Kebir on July 6. In the raid, the patrol boat Terre-Neuve exploded near Dunkerque causing additional damage.

Aftermath of Mers el Kebir

To the east, Admiral Sir Andrew Cunningham was able to avoid a similar situation with the French ships at Alexandria. In hours of tense talks with Admiral René-Emile Godfroy, he was able to convince the French to allow their ships to be interned. In the fighting at Mers el Kebir, the French lost 1,297 killed and around 250 wounded, while the British incurred two killed. The attack badly strained Franco-British relations as did an attack on the battleship Richelieu at Dakar later that month. Though Somerville stated "we all feel thoroughly ashamed," the attack was a signal to the international community that Britain intended to fight on alone. This was reinforced by its stand during the Battle of Britain later that summer. Dunkerque, Provence, and Mogador received temporary repairs and later sailed for Toulon. The threat of the French fleet ceased to be an issue when its officers scuttled its ships in 1942 to prevent their use by the Germans.

Selected Sources

mla apa chicago
Your Citation
Hickman, Kennedy. "World War II: Attack on Mers el Kebir." ThoughtCo, Aug. 26, 2020, Hickman, Kennedy. (2020, August 26). World War II: Attack on Mers el Kebir. Retrieved from Hickman, Kennedy. "World War II: Attack on Mers el Kebir." ThoughtCo. (accessed June 8, 2023).