1940 Mers-el-Kebir Attack: British Treachery Or Preemptive Strike?

The attack on the port of Mers-el-Kebir on 3 July 1940, has gone down as either a courageous decision that saved Britain — or a treacherous and needless backstab of an ally.

During that chaotic summer, the situation looked grim. The German blitzkrieg had just conquered France and Western Europe, while the cream of the British Army had barely been evacuated — minus their equipment — from Dunkirk. If the Germans could launch an amphibious assault across the English Channel, the British Army was in no condition to repel them.

However, Operation Sealion — the Nazi German plan to invade Britain — had its own problems. The Kriegsmarine — the German Navy — was a fraction of the size of the Royal Navy, and thus too small to escort vulnerable troop transports. But Britain's Prime Minister Winston Churchill had to contemplate a situation he had never expected: a combined German-French battlefleet.

Technically, France had only agreed to an armistice — a permanent cease-fire — with Germany rather than surrender. France would be divided between German-occupied northern zone, and a nominally independent rump state of Vichy comprising southern France and the colonies of the French Empire. Vichy France would be allowed a meager army, and the French Navy would be confined to its home ports.

The British didn't trust French promises that its ships would be scuttled if the Germans tried to seize them. Why had France signed a separate peace with Germany after earlier pledging not to? Why didn't the French government choose to go into exile, and continue the war from its North African colonies as the British urged?

London was well aware that the right-wing Vichy government — under Field Marshal Philippe Pétain, hero of the First World War — had more affection for the Third Reich than it did for Britain. With Germany master of Europe, Pétain sneered that Britain would soon "have its neck wrung like a chicken."

After Vichy rebuffed pleas to send the fleet to British ports, Churchill and his ministers decided the risk was too great. In late June 1940, the Royal Navy received orders for Operation Catapult. A task force — including the aircraft carrier Ark Royal and three battleships and battlecruisers — would be dispatched to the French naval base at Mers-el-Kebir, near the Algerian port of Oran. A powerful French squadron of four battleships and six destroyers were docked there, including the new battleships Dunkerque and Strasbourg.

The French were to be given six hours to respond to an ultimatum: sail their ships to British ports and fight the Germans, sail them to French Caribbean ports and sit out the war, demilitarize their ships at Mers-el-Kebir, or scuttle their vessels. When the local French commander tried to delay while summoning reinforcements, the British opened fire.

The ensuing battle was not the Royal Navy's most glorious. Caught in every admiral's nightmare — unprepared ships anchored in port — the French were simply smothered by British gunfire. The battleship Bretagne and two destroyers were sunk, two other battleships damaged, and 1,297 French sailors perished. The British suffered two dead.

Most ships at Mers-el-Kebir were damaged rather than sunk, and the French fleet quickly relocated its scattered vessels to the heavily defended French port at Toulon (where they were scuttled in November 1942 when German troops occupied Vichy). Though Vichy didn't declare war on Britain — and only retaliated with a few minor attacks on British bases — it confirmed old French prejudices about British treachery and "perfidious Albion."

Britain's attack on Mers-el-Kebir was political as much as military. In the summer of 1940, many people — including some in the United States — believed that the British would be conquered or compelled to make peace with a victorious Germany. Churchill argued that Britain had to show its resolve to keep on fighting, not least if it hoped to persuade America to send tanks, ships and war materials via a Lend-Lease deal. Attacking a former ally may have been a demonstration of British resolve.