When Britain's empire went to war in August 1914, rugby players were the first to volunteer: they led from the front and paid a disproportionate price.
When the Armistice came after four long years, their war game was over; even as the last echo of the guns of November faded, it was time to play rugby again. As Allied troops of all nations waited to return home, sport occupied their minds and bodies.
In 1919, a grateful Mother Country hosted a rugby tournament for the King's Cup, to be presented by King George V at Twickenham Stadium.
It was a moment of triumph, a celebration of military victory, of Allied unity and of rugby values, moral and physical.
Never before had teams from Australia, Canada, New Zealand, South Africa, Britain and France been assembled in one place.
Rugby held the first ever `World Cup' - football would not play its own version until 1930. In 2015 the modern Rugby World Cup returns to England and Twickenham as the world remembers the Centenary of the Great War.
With a foreword by Jason Leonard, this is the story of rugby's journey through the First World War to its first World Cup, and how those values endure today.