that Churchill speech

The earlier section is just as relevant as the later, more remembered, section:

Turning once again, and this time more generally, to the question of invasion, I would observe that there has never been a period in all these long centuries of which we boast when an absolute guarantee against invasion, still less against serious raids, could have been given to our people. In the days of Napoleon, of which I was speaking just now, the same wind which would have carried his transports across the Channel might have driven away the blockading fleet. There was always the chance, and it is that chance which has excited and befooled the imaginations of many Continental tyrants. Many are the tales that are told. We are assured that novel methods will be adopted, and when we see the originality of malice, the ingenuity of aggression, which our enemy displays, we may certainly prepare ourselves for every kind of novel stratagem and every kind of brutal and treacherous manœuvre. I think that no idea is so outlandish that it should not be considered and viewed with a searching, but at the same time, I hope, with a steady eye. We must never forget the solid assurances of sea power and those which belong to air power if it can be locally exercised.

I have, myself, full confidence that if all do their duty, if nothing is neglected, and if the best arrangements are made, as they are being made, we shall prove ourselves once more able to defend our island home, to ride out the storm of war, and to outlive the menace of tyranny, if necessary for years, if necessary alone.