It is one of our most cherished national myths: Britain, standing alone in the darkest days of the Second World War, sustained only by the rhetoric, passion and willpower of its greatest prime minister. In the words of William Rees-Mogg, recalling a childhood spent glued to the radio, Churchill's speeches "persuaded the country as a whole that the Nazi regime was wholly evil; that there could be no security in surrender". In doing so, "they saved Britain and, through Britain, they saved the world". Except that, according to Richard Toye, a history professor from the University of Exeter, it didn't happen that way at all.
In The Roar of the Lion, his new book on Churchill's wartime speeches, he argues that, for all the rhetorical flourishes, "there is little evidence that they made a decisive difference to the British people's will to fight". During the "finest hour" speech, delivered on June 18 1940, in the wake of France's surrender, many thought the prime minister was drunk (perhaps because he delivered the text, a copy of his speech that day to Parliament, while working his way through a large cigar). The Labour MP Harold Nicolson thought Churchill sounded "ghastly". Cecil King, the newspaper baron, considered it "the poorest possible effort". In general, the reviews were kinder, but Toye has something of a point. While a solid majority of the population did tune in to Churchill's speeches on the radio, what they were listening for were his all-important - and surprisingly honest - updates on the progress of the war, which actually formed the bulk of the content. The high-flown oratory, they could take or leave. It's one of our most cherished ideas that a single person can, by words alone, change the course of history. But it happens much less often than you might think. Roosevelt's "fireside chats", for example, were long thought to have rallied the American nation during the Depression.
But, in his recent book On Deaf Ears: the Limits of the Bully Pulpit, George Edwards insists that their effect has been exaggerated, not least since FDR gave only two or three such talks a year. Even then, his radio addresses failed to add more than a percentage point to his approval rating. It takes nothing away from Churchill's rhetorical genius to point out that many speeches, his included, aren't so much born great as become so. Real life isn't like the conclusion of The King's Speech, with everyone from the humblest urchin to the grandest toff listening to their leader in silent rapture. There will always be those in the audience who aren't interested, or have better things to do. Yet somehow, sometimes, the words strike a chord, one that reverberates more and more strongly as the years go by. Take probably the most famous political speech in history: the Gettysburg Address. At just over two minutes, it is a model of miraculous concision (so much so that my English teacher once challenged us to find a single surplus phrase; no one could). But initially, the reviews were mixed, partly because of its very brevity. While newspapers loyal to Lincoln's Republicans cheered it to the skies, those who supported the opposition were less kind. "The cheek of every American must tingle with shame as he reads the silly, flat and dishwatery utterances of the man who has to be pointed out to intelligent foreigners as the President of the United States," said The Chicago Times.
Its namesake in London - displaying its traditional good judgment - claimed that "the ceremony was rendered ludicrous by some of the sallies of that poor President Lincoln. Anything more dull and commonplace it would not be easy to produce." How, then, did it enter the history books? Partly because people came to recognise the perfection of its structure. And partly through repetition and circulation, which can be all-important. For instance, Lincoln rose to fame via his pre-Civil War election debates over slavery with Stephen Douglas.
But for all Lincoln's oratory, it was Douglas who won their race for the Senate. It was the wider publicity fuelled by Lincoln's publication of edited transcripts of the debates - which became a huge best-seller - that led to his nomination for president. Another golden rule is that a speech has to be given at the right moment - and by the right side. Queen Elizabeth's greatest act of oratory came when she dressed herself in armour and paraded before the troops at Tilbury, pronouncing that, while she might have the body of a weak and feeble woman, "I have the heart and stomach of a king, and of a king of England too." The cheers were real, and heartfelt - but it greatly helped matters that the Armada had already been dispersed by storms. Of course, it would be stretching matters to argue that victory is all that matters. If Iain Duncan Smith had won a landslide victory in 2005, or Neil Kinnock in 1992, we would not be talking about "the quiet man is here to stay, and he's turning up the volume" or "We're awright!" as the new "Blood, toil, sweat and tears". No, the speeches that become part of the warp and weft of our history, like Churchill's and Lincoln's, do so because they reflect values and ideals that we cherish today. Elizabeth's address at Tilbury, like its fictional echo in Henry V ("Cry God for Harry, England and St George!") still stirs the blood because we still love our country. Churchill's speech defending Operation Catapult, which saw the Royal Navy wipe out the French fleet lest it fall into German hands, was - as Prof Toye points out - every bit as well-known in 1940 as "Fight them on the beaches" et al. Because it fails to fit into the preferred narrative, it has dropped off the radar. Yet sometimes, even today, a speech cuts through the chatter - is so powerful, and so stirring, that even those listening at the time know that they have heard something extraordinary.
Starting with his speech to the Democratic convention in 2004, in which he castigated the division of America into red states and blue states, Barack Obama rode to the presidency on a wave of words that felt immediate, clear and absolutely right. Brian MacArthur, editor of the Penguin Book of Modern Speeches, also cites Earl Spencer's speech in Westminster Abbey over the catafalque of his dead sister. It was, he says, "so deeply felt that the masses outside the Abbey started applauding - before the sound of the applause penetrated the Abbey and the congregation joined in". When lightning does strike, it is an experience that few forget.
Reviews for John F Kennedy's inaugural address, in which he urged Americans to "ask not what your country can do for you", were universally rapturous. And then there was Martin Luther King's "I have a dream" speech, delivered 50 years ago next week, on the steps - fittingly - of the Lincoln Memorial. Yet even here, the myth has obscured the fact. The truth is that King's speech that day was something of a dud: pulled together at the last minute, it was decent and workmanlike, but far from hitting his usual heights. Still, thought his adviser Wyatt Walker during the preparations, at least he hadn't used that line about having a dream that he'd trotted out a few times before, without generating much enthusiasm.
He'd told King: "It's trite, it's cliche. You've used it too many times already." Then the draft of the speech was typed up. According to an article by Clarence Jones, one of King's team, something magical happened. As King was reaching his peroration, "Martin's favourite gospel singer, Mahalia Jackson… called to him from nearby: 'Tell 'em about the dream, Martin, tell 'em about the dream!'?" "Martin clutched the speaker's lectern and seemed to reset. I watched him push the text of his prepared remarks to one side. I knew this performance had just been given over to the spirit of the moment. I leaned over and said to the person next to me: 'These people out there today don't know it yet, but they're about ready to go to church.'?" In front of his eyes, King transformed from teacher to preacher, abandoning his set text and speaking the words that would define his legacy: "I have a dream…" Kennedy died in 1963, and King in 1968. In so doing, their images, and their words, were frozen in time: symbols of inspiration untarnished by subsequent disappointment. For all Obama's rhetorical gifts, it is strangely hard to associate him now with one single phrase: the simplicity of "Yes We Can" or the majesty of talk of "the moral arc of the universe" sit strangely alongside the weary compromises of governing.
More broadly, the great speech sometimes seems to be an endangered species. In politics, the advent of television has led to the excision of passages in favour of devastating zingers, or verbless sentences. On American news programmes, the length of the average political soundbite has dropped from more than 40 seconds in the late Sixties to less than 10: perfect for "Where's the beef?" or "Read my lips: no new taxes", less so for "Four score and seven years ago…" In Britain, modern speeches are - according to Danny Kruger, a former speechwriter for David Cameron - "often just vehicles for a policy announcement or a soundbite".
We should not be too downheartened, however. We will never be rid of rhetoric, because it fulfils an eternal human need. And sometimes, in the hands of the right speaker, at the right time, it really can change the world.