A year ago Professor Sarah Churchwell, public engagement chair at the School of Advanced Study and professorial fellow in American literature at its Institute of English Studies, thought she knew what she would be doing – in terms of big projects at least – for 2017. And it didn’t include writing the book she has just finished, which traces the rhetorical history of two key US slogans, ‘America first’ and the ‘American dream’.

Last February, I gave a lecture at the Institute of English Studies (IES) in conjunction with the Princeton Alumni Association of the UK. It brought together some research I had been doing for some time on the history of the American dream, as a phrase, which came out of my previous monograph, Careless People. That book tells the story of how F. Scott Fitzgerald came to write The Great Gatsby, and how it reflected the world of 1920s America.

As Donald Trump came to dominate the story of American politics and culture throughout 2016, I had increasingly been speaking and writing about how his rise dovetailed in important ways with that research. So at the IES lecture I decided to tie all the pieces together, lay it all out in one clear narrative, and explain what I thought this history had to tell us about the rise of Trump.

I was surprised when I finished it at how much there seemed to me to it; the audience’s response confirmed that feeling. Within a few weeks I found myself pitching a BBC Radio 4 documentary around the same ideas, and in early March was in New York, interviewing other academics for it. One of them, a professor of American history at NYU, asked if I was writing a book about the subject. I decided I should, and began pulling together my research notes, journalism, and lectures on the topic. Bloomsbury wanted to publish it, and before I knew it I was researching and producing a draft. I had agreed a short book with Bloomsbury – around the length of The Great Gatsby, in fact – which I expected I could produce with relative ease. Famous last words: as I began researching in earnest I found, as is sometimes the case, that the story I had to tell was much bigger, much richer, and seemed (to me at least) far more important than I had anticipated.

Behold, America: A History of America First and the American Dream is the result. It draws almost entirely on newspapers between about 1895 and 1941, when the United States entered the Second World War, to trace the emergence of these two phrases – America first and the American dream – that speak to so much of American cultural life today, and that symbolise the nation’s cultural divide. It turns out that the history of both phrases is far more surprising than anyone – myself very much included – expected.

Tracing the origins of these phrases in the progressive and populist reform movements of the early 1900s, and the part they played in the debates about America’s role in the First World War, the book offers a genealogy that challenges received wisdom about expressions that have become clichés in American political life.

The American dream did not always mean what we think it means – far from it. And America first is far older, and darker, than we’ve been led to believe by pundits and journalists commenting on its sudden rise as Trump’s slogan. Behold, America traces both slogans through America’s debates about its meanings and role in the world, from progressive reform through isolationism, from nativism and the rise of the KKK through the boom of the 1920s to the Depression of the 1930s, from the New Deal to the rise of European fascism, as the United States had to decide what role it would play in the fight between democracy and totalitarianism. Both the American dream and America first were enlisted in all of these battles.

It turns out that America first and the American dream were always connected, and contested, terms in a nation that was finding its way. Behold, America argues that a nation losing its way might do well to contest these expressions once more; they have much to teach us about what America used to mean, and what it might mean again.

Sarah Churchwell is professor of American literature and chair of public understanding of the humanities at the School of Advanced Study, University of London. She is the author of Careless People: Murder, Mayhem and The Invention of The Great Gatsby and The Many Lives of Marilyn Monroe. She writes regularly for newspapers including the Guardian, New Statesman, Financial Times, Times Literary Supplement and New York Times Book Review, and comments on arts, culture and politics for television and radio, where appearances include Question Time, Newsnight and The Review Show. She has judged many literary prizes such as the 2017 Baillie Gifford Prize for Nonfiction, the 2014 Man Booker Prize for Fiction, and she was co-winner of the 2015 Eccles British Library Writer’s Award. Her new book, Behold, America: A History of America First and the American Dream, will be published by Bloomsbury in May 2018.