In 1940 the Royal Navy destroyed a large part of the French fleet at anchor in Mers-el-Kébir. Why did this happen, as I understand it Churchill didn't want it to fall into German hands but was there more going on?
Furthermore how is the event interpreted today in France and in the UK. Its not something I see much debate about.
GB could not allow the German navy to roam free in the atlantic. In general that strategy was to lock them up in port and keep them there till the war was over. The addition of the french fleet would have made that impossible for the Navy to do as it was already stretched thin.
As to the reasons.
Admiral Darlan and the french could not be trusted. Churchill could not and would not allow the french fleet to fall in German hands. Darlan promised churchill that if the Germans attempted to sieze the fleet he would scuttle the whole thing rather then hand it over. Churchill could not afford to or did not want to take his word for it. Of note it seems for all his faults Darlan did have the last laugh after Toulon where he did in fact do what he promised to do. "Prime Minister you said to me 'I hope you will never surrender the fleet'. I replied, 'There is no question of doing so'. It seems to me you did not believe my word. The destruction of the fleet at Toulon has just proved that I was right.
Another issue was to show the USA that GB was capable of doing what was necessary no matter the costs. In 1940, the war was not exactly going the allied way and Churchill was trying to convince the US to join the fight without much success. With Mers-el-Kebir he was able to show the hesitant FDR that he was serious and GB was not going to roll over.