Churchill's challenge was to overcome, not defeatism, but the "puzzlement, boredom and slackness" of the "first generation in European history which had been brought up to expect that there would not be another war." America today is desperately in need of a clarion call that will rouse us from our lethargy and remind us, clearly and definitively, that we too are in a fight for our lives.
There are other lessons to be gleaned from those years: the cost of military un-preparedness; the fantasy that evil can be appeased; the romantic notion that enslaved people will rise up against their oppressors are but a few. Churchill's unifying gesture in making his predecessor the discredited Neville Chamberlain a member of his War Cabinet, a man for whom he nonetheless felt much sympathy, is an example many of today's politicians might follow.
Perhaps the overriding lesson is this: those who can't remember the past are condemned to repeat it.