Recently hearing about a speech President Nixon had prepared in case the Apollo 11 mission failed has piqued my interest in this sort of real responses to 'what if' scenarios.
Nuclear war seems kind of like it would have been a big one. Did any world leaders have a sort of doomsday speech tucked away in a drawer some where in case the worst happened, and they didn't have time to actually write one? And did any of these survive and are public?
Or was it the sort of thing people just didn't want to think about, and figured would probably be a fairly small concern if it ever really happened?
OP, please excuse my formatting, but I'm posting this from a phone.
The best example I can provide is probably JFK's 1962 draft speech during the Cuban Missile Crisis that would have informed the American public that he had chosen to remove Soviet nuclear weapons from Cuba via military strikes. There was great fear that such an act would have provoked the Soviet government to respond militarily, possibly leading to a nuclear war. The draft was released a few years ago. Here is an article, with a link to the speech text from the Kennedy Library.
http://www.rferl.mobi/a/speech-that-wasnt-kennedy-prepared-speech-cuban-missile-crisis/24744628.html
Yes, there was a speech prepared for Queen Elizabeth II to deliver in the event nuclear war was likely. It was made up as part of an exercise but certainly it or something similar would have been used in the real situation, assuming there was a chance to use it. So in the UK in the 1980s you would have known you were in big trouble if you heard a speech like that and started to see the "Protect and Survive" PSAs on television.
Related to this are the Letters of Last Resort used by the British government. Identical letters written by the Prime Minister were put in safes on each of the UK's four nuclear-armed submarines, to be opened in the event that the UK itself (or at least her government) were totally wiped out.
They were destroyed unread when each successive PM came into office, so we don't know what any of them said.