Vivid depiction of Versailles conference wins £30,000 prize for non-fiction

In a year when blood-curdling tales of battle are filling the ranks of bestsellers, Britain's most generous literary award for non-fiction has gone to a study of how to end wars, rather than wage them.

Peacemakers, a history of the Versailles conference of 1919 by the Canadian historian Margaret MacMillan, became the fourth winner of the £30,000 Samuel Johnson prize for non-fiction yesterday.

MacMillan, a distant outsider on the shortlist until the end of last week, beat the strongly tipped favourite, Roy Jenkins's epic biography of the country's greatest war leader, Winston Churchill.

The first victor of the Samuel Johnson prize was Stalingrad by Antony Beevor, in 1999. Last year, it went to Michael Burleigh's The Third Reich, a new history. Faithfully reflecting the popular taste for grand 20th-century narratives expressed in book sales and television ratings, the prize has gone in three years out of four to large-scale accounts of European history between the end of the First and Second World Wars.

This year's result was announced by the chairman of the judges, David Dimbleby, at a dinner televised by the new sponsors of the prize, BBC4. He praised Peacemakers for "bringing vividly to life an extraordinary event which shaped the 20th century and still resonates today". His fellow judges included the playwright and broadcaster Bonnie Greer, and the novelist and journalist Robert Harris.

Peacemakers, published by John Murray, tells the story of the conference outside Paris that tried to fashion an enduring settlement for Europe and the wider world out of the ruins left by the First World War. Writing with dramatic gusto and a keen eye for character and incident, Professor MacMillan examines the intrigues of the leading players – Lloyd George from Britain, Georges Clemenceau from France, Woodrow Wilson from the US. She passes an unusually kindly judgement on them.

Previous historians have often seen the botched arrangements of Versailles as a trigger for the German resentment that culminated in the rise of Hitler and another, even deadlier, war. MacMillan spurns such hindsight as she dramatises the actions of confused politicians who had "to deal with reality, not what might have been".

In particular, she challenges the widely accepted view, first espoused by John Maynard Keynes, that the "harshness" of the Versailles Treaty towards Germany ultimately led to the Nazi takeover. Peacemakers even suggests that, if their aim was long-term peace in Europe, the Versailles negotiators were not harsh enough.

Margaret MacMillan, professor of history at Ryerson University, Toronto, will shortly take up the post of provost of Trinity College at Toronto University. She is the first woman to win the prize. The other shortlisted titles were The Voices of Morebath by Eamon Duffy (Yale University Press); The Snow Geese by William Fiennes (Picador); The Invention of Clouds by Richard Hamblyn (Picador); Churchill by Roy Jenkins (Macmillan); and Unfinest Hour by Brendan Simms (Allen Lane).