On this day 1940 the @RoyalNavy's Gibraltar-based Force H, formed just 3 days before under V/Adm Sir James Somerville with the battlecruiser HMS Hood, aircraft carrier HMS Ark Royal & battleships HMS Valiant & HMS Resolution, bombarded the French Force de Raid at Oran, Algeria

The bombardment was aimed at neutralising the most powerful force in the French Navy, the Force de Raid under V/Amd Marcel-Bruno Gensoul, with the new battlecruisers Dunkerque, Strasbourg & the old battleships Bretagne & Provence to prevent them from falling into German hands...

due to serious British fears that the promise that had been given by French naval CinC Adm Francois Darlan to 1st Sea Lord Adm/Flt Sir Dudley Pound in Bordeaux just before the Franco-German Armistice, would prove to be rather less solid than hoped. https://twitter.com/navalhistorian/status/1273727095974264832?s=20

V/Adm Somerville had presented V/Adm Gensoul with the British Government's ultimatum that morning:
"a) Sail with us and continue to fight for victory against the Germans and Italians.
b) Sail with reduced crews under our control to British ports. The reduced crew will be...

repatriated at the earliest moment. If either of these courses is adopted by you we will restore your ships to France at the conclusion of the war, or pay for compensation if they are damaged meanwhile.
c) Alternatively, if you feel bound to stipulate that your ships should not

be used against Germans or Italians, since this would break the Armistice, then sail them with their us with reduced crews to some French port in the West Indies - Martinique, for instance - where they can be demilitarised to our satisfaction, or perhaps be entrusted to the...

United States of America, and remain safely until the end of the war, the crew being repatriated.
If you refuse these fair offers, I must with profound regret require you to sink your ships within six hours. Finally, failing the above I have orders from HM Government to use...

whatever force may be necessary to prevent your ships from falling into German or Italian hands."
V/Adm Gensoul declined, reiterating the orders he had recieved from Adm Darlan to ensure the fleet did not fall into German hands & urging Somerville 'Do not create the irreparable'.

But V/Adm Somerville was also being urged by the Prime Minister & 1st Sea Lord to "settle matters quickly", & at 1754 Force H opened fire with their 15in guns. Bretagne was destroyed in a magazine explosion, while Provence & Dunkerque were severely damaged. 1,297 were killed.

Strasbourg however, esaped to Toulon, following a brief chase by HMS Hood & a half-hearted air strike by Swordfish torpedo bombers from HMS Ark Royal.
"I shouldn't be surprised if I was relieved forthwith [for not sinking Strasbourg]" wrote the distraught Somerville to his wife..

"I don't mind because it was an absolutely bloody business to shoot up these Frenchemen who showed the greatest gallantry. The truth is my heart wasn't in it & you're not allowed a heart in war."