Operation Catapult. At dawn, Royal Navy boards 2 French battleships, 9 destroyers and other smaller ships at Plymouth and Portsmouth, England (3 British & 1 French sailor are killed).
At 5.45 AM, British Force H arrives off Mers-el-Kébir, Algeria. Vice Admiral Somerville offers French Admiral Marcel Gensoul (a known Anglophobe, loyal to the Vichy government) four alternatives for his fleet; join the Royal Navy; be interned in British ports, be decommissioned in the West Indies or USA, or sink the warships in Mers-el-Kebir harbour. Gensoul rejects the British terms, leading to fruitless negotiations all afternoon. At 5.56 PM, British ships shell the harbour for 10 minutes. The magazine on French battleship Bretagne is hit, which explodes and sinks at 6.09 PM (977 lives lost). Battleships Provence and Dunkerque and destroyer Mogador are damaged. In all, 1,297 French sailors are killed and 350 wounded. http://www.hmshood.org.uk/reference/official/adm234/adm234-317.htm
French battleship Strasbourg, aircraft carrier Commandant Teste and four destroyers escape from Mers-el-Kébir following the attack and evade the British blockade. 6 French cruisers and 4 destroyers leave Algiers on the news. They rendezvous and escape to Toulon, France, arriving on 4 July, despite bombing attacks by Fairey Swordfish from British aircraft carrier HMS Ark Royal.
Similar terms are given by Vice Admiral Sir Andrew Cunnigham to French Admiral Godefroy at Alexandria, Egypt. Negotiations continue all day and the French ships (battleship Lorraine and 4 cruisers) are not attacked. Negotiations will continue until July 7.
Luftwaffe bombs Cardiff in South Wales.