When Winston Churchill visited his old school to address it in 1942, it is commonly thought that his entire talk consisted of a memorable encouragement never, never to give up.
You can hear his gravelly growly voice declaiming those words! In fact they were part of a slightly longer – though still commendably brief talk. Here is the memorable talk he gave to the boys:
We cannot tell from appearances how things will go. Sometimes imagination makes things out to be far worse than they are; and yet without imagination not much can be done. People who are imaginative see many more dangers than perhaps exist; certainly many more than will happen; but then they must also pray to be given that extra courage to carry this far-reaching imagination.
For everyone who has lived through these [last turbulent months of the war], this is the lesson: never give in, never give in, never, never, never, never; in nothing, great or small, large or petty: never give in except to convictions of honour and good sense. Never yield to force; never yield to the apparently overwhelming might of the enemy. (churchill-society-london.org.uk)
See also Your Troops will be Willing