On June 18, 1940, Winston Churchill's "this was their finest hour" speech urging perseverance during the Battle of Britain was delivered to the British House of Commons. Here is the end of his rather long speech.
"We do not yet know what will happen in France or whether the French resistance will be prolonged, both in France and in the French Empire overseas. The French Government will be throwing away great opportunities and casting adrift their future if they do not continue the war in accordance with their Treaty obligations, from which we have not felt able to release them. The House will have read the historic declaration in which, at the desire of many Frenchmen-and of our own hearts-we have proclaimed our willingness at the darkest hour in French history to conclude a union of common citizenship in this struggle. However matters may go in France or with the French Government, or other French Governments, we in this Island and in the British Empire will never lose our sense of comradeship with the French people. If we are now called upon to endure what they have been suffering, we shall emulate their courage, and if final victory rewards our toils they shall share the gains, aye, and freedom shall be restored to all. We abate nothing of our just demands; not one jot or tittle do we recede. Czechs, Poles, Norwegians, Dutch, Belgians have joined their causes to our own. All these shall be restored.
What General Weygand called the Battle of France is over. I expect that the Battle of Britain is about to begin. Upon this battle depends the survival of Christian civilization. Upon it depends our own British life, and the long continuity of our institutions and our Empire. The whole fury and might of the enemy must very soon be turned on us. Hitler knows that he will have to break us in this Island or lose the war. If we can stand up to him, all Europe may be free and the life of the world may move forward into broad, sunlit uplands. But if we fail, then the whole world, including the United States, including all that we have known and cared for, will sink into the abyss of a new Dark Age made more sinister, and perhaps more protracted, by the lights of perverted science. Let us therefore brace ourselves to our duties, and so bear ourselves that, if the British Empire and its Commonwealth last for a thousand years, men will still say, 'This was their finest hour.'”