In May 1940, Adolf Hitler and his Nazi war machine were sweeping across the European continent.

The future of the free world hung in the balance.

An isolationist-leaning United States was an ocean away. There was one man who stood between Hitler’s seemingly invincible army and crushing defeat.

That one man was Winston Churchill.

He was born on November 30, 1874. Though we think of him as the quintessential Englishman, he was actually half American.

His mother, Jennie, was the daughter of a wealthy New York stock speculator. His father, Lord Randolph Churchill, was of English nobility and a major political figure.

From his early school days, Churchill recognized the power of words. Throughout his life, he used them with consummate skill. They never let him down.

He first made a name for himself as a war correspondent in the 1890s, covering conflicts in Cuba, Northern India, the Sudan, and South Africa. Though he never abandoned journalism, and became one the greatest historians of his age, Churchill used his family connections and his own fame to launch himself into politics. His confident manner and matchless oratory marked him as a natural leader.

1914 and World War I found him in the key position of First Lord of the Admiralty where he did much to modernize Britain’s navy. In 1915, Churchill thought he could bring a speedy end to the war by opening a new front in Turkey, which he perceived as the weak link in the German alliance against the allies.

This led to the infamous Gallipoli campaign.

Badly underestimating the fighting strength of the Turks, thousands of British, Australian and New Zealand soldiers were killed in battles that proved to be every bit as indecisive and bloody as the campaigns on Europe’s Western front.

Churchill took the blame.

This was perhaps the low point of his life. Dismissed from the war cabinet, five months later he enlisted in the army, where he saw action in France.

He rose again in British politics throughout the 1920s, making money—as he always did—through his writing and speaking. As Adolph Hitler took power in Germany in the 1930s, Churchill was one of the first and certainly the loudest voice in England sounding the alarm. But it was an alarm few in England wanted to hear.

The English had been traumatized, as had all of Europe, by the shocking amount of death and destruction of the First World War. No one wanted to face the possibility that it could happen again.

Churchill, however, saw that a new confrontation with Germany was inevitable. And when the inevitable arrived with the stunning German attack on France in May 1940, a desperate nation turned to him. He was ready.

His weapons were his pen, his voice and his words. “I have nothing to offer but blood, toil, tears and sweat,” he told the House of Commons in his first speech as Prime Minister.

Things quickly turned from bad to worse. France collapsed, Belgium surrendered, and a quarter of a million British soldiers barely managed to escape from Dunkirk. Even as the war news moved from dangerous to desperate to disastrous, Churchill never wavered. In speech after speech, he infused the British with the spirit to fight on against Hitler’s monstrous tyranny.

“We shall not flag or fail,” he said after Dunkirk. “We shall go on to the end. We shall defend our island, whatever the cost may be…we shall never surrender.”

The point about Churchill in 1940 is not that he stopped a German invasion, but that he stopped the British Government making peace. If Churchill had not been Prime Minister, the pro-appeasement foreign secretary Lord Halifax would have been.

We know that Halifax was open to negotiating with Hitler. We’d be mistaken to assume that the German Fuhrer’s terms would not have been reasonable; they would probably have been very reasonable, as Hitler wanted to fight a one-front war against Russia. And an agreement with Britain would have allowed him to do just that.

Churchill made this impossible.

Had he not rallied the British people in the face of defeat after defeat, preventing Hitler from concentrating his full efforts on Russia, the entire history of the free world would have been much different. And, undoubtedly, much darker.

Because of Churchill’s efforts and the marvelous resilience of the British people, the United States had an unsinkable “aircraft carrier” —Britain— from which to mount the liberation of the European continent in June of 1944.

For this and so much more, free people everywhere can thank the greatest man of his age—Winston Churchill.

I’m Andrew Roberts for Prager University.