N.B. “Be Ye Men of Valour” is from the original Appendix IV in my book Churchill By Himself. It was deleted in the later edition, Churchill in His Own Words, to make room for an index of phrases. Concluded from Part 2…
From the Book of Maccabees
On 19 May 1940, Churchill made his first broadcast as Prime Minister, a speech which lifted the hearts even of former critics:
A tremendous battle is raging in France and Flanders. The Germans, by a remarkable combination of air bombing and heavily armoured tanks, have broken through the French defences north of the Maginot Line, and strong columns of their armoured vehicles are ravaging the open country, which for the first day or two was without defenders. They have penetrated deeply and spread alarm and confusion in their track. Behind them there are now appearing infantry in lorries, and behind them, again, the large masses are moving forward.
In assuring his listeners that Britain would fight on, Churchill chose a majestic but obscure Biblical allusion. It was his first and only use of it. It proved to be exactly right for the occasion:
Today is Trinity Sunday. Centuries ago words were written to be a call and a spur to the faithful servants of Truth and Justice: “Arm yourselves, and be ye men of valour, and be in readiness for the conflict; for it is better for us to perish in battle than to look upon the Outrage of our nation and our altar. As the Will of God is in Heaven, even so let it be.
Origins: “Men of Valour”
Even some Biblical scholars were uncertain about the origins of this phrase, and with good reason. It is from the First Book of the Maccabees, a text missing in many Bibles. Also, Churchill altered the quotation. He either remembered badly, or the writer in him could not resist an editorial improvement. The original words were:
58. And Judas said, Arm yourselves, and be valiant men, and see that ye be in readiness against the morning, that ye may fight with these nations, that are assembled together against us to destroy us and our sanctuary: 59. For it is better for us to die in battle, than to behold the calamities of our people and our sanctuary. 60. Nevertheless, as the will of God is in heaven, so let him do.
There are two Books of the Maccabees, also spelled “Machabbes,” neither of which is in the Hebrew Bible but both of which appear in some manuscripts of the Septuagint and in the Vulgate, since they are canonical to Roman Catholicism and Eastern Orthodoxy. They are also included in the King James Apocrypha, which is where Churchill read them.
Churchill’s first broadcast as Prime Minister caught the imagination of millions. Sir Martin Gilbert has collected some of those reactions that very evening, Trinity Sunday, 19 May, 1940,
Anthony Eden wrote: “You have never done anything as good or as great. Thank you, and thank God for you.” Lord Halifax, who nine days later would urge approaching the Germans for an armistice, was momentarily bowled over: “It was worth a lot,” he wrote from the Foreign Office, “and we owe you much for that, as for a great deal else, in these dark days.” The Evening Standard declared the broadcast a speech of “imperishable resolve.”
The most unexpected was a note from Churchill’s old chief and sometime nemesis Stanley Baldwin, who had done more than any other British leader to put the country in so perilous a state of readiness, but who on 19 May was moved more perhaps than any other:
My dear PM, I listened to your well known voice last night and I should have liked to have shaken your hand for a brief moment and to tell you that from the bottom of my heart I wish you all that is good—health and strength of mind and body—for the intolerable burden that now lies on you. Yours always sincerely, SB 
11. Winston S. Churchill, Broadcast, London, 19 May 1940, in Robert Rhodes James, ed., Winston S. Churchill: His Complete Speeches 1897-1963, 8 vols. (New York: Bowker, 1974), VI: 6221.
12. Ibid., 6223.
13. King James Bible, 1611: I Maccabees 3:58-60
14.Martin Gilbert, Winston S. Churchill, vol. 6, Finest Hour 1939-1941 (Hillsdale, Mich.: Hillsdale College Press, 2011), 365.