On this day in 1940, British naval forces destroy the French fleet at Mers-el-Kebir, a port in Algeria, in order to prevent Germany from co-opting the French ships to use in an invasion of Britain.
With the occupation of France, the German aggressor was but a Channel away from Britain. In order to prevent the Germans from using French battleships and cruisers in an attack on Britain, Operation Catapult was conceived: the destruction or capture of every French ship possible. The easiest stage of Catapult was the seizure of those French ships already in British ports. Little resistance was met. But the largest concentration of French warships was at the Oran, Algeria, port of Mers-el-Kebir, where many warships had fled to escape the Germans. This stage of Catapult would prove more difficult.
Britain gave the French ships four choices: join British naval forces in the fight against Germany; hand the ships over to British crews; disarm them; or scuttle them, making them useless to the Germans. The French refused all four choices. Britain then made a concession: Sail to the French West Indies, where the ships would be disarmed or handed over to the United States. The French refused again. So the Brits circled the port and opened fire on the French fleet, killing 1,250 French sailors, damaging the battleship Dunkerque and destroying the Bretagne and the Provence.
On July 4, British Prime Minister Winston Churchill told the House of Commons that he would leave Britain's actions to "history." On July 5, Vichy France broke off diplomatic relations with Britain.