Capturing the defining moment of the twentieth century is an interesting game to play. Some say it was when India was handed over to Congress, thus setting an example to nationalists in Africa, Latin America and the Far East. Others say the defining moment was when Adolf Hitler killed himself in 1945, ending the short, terrifying career of Fascism and Nazism which have so driven the century.

Academics say it was when America picked up the glove thrown down by Britain's sulky imperialists after the Second World War. Many a politically-correct professor warms the hearts of professional egalitarians by pointing to 1957 when Ghana's Kwame Nkrumah hand-started black ''socialism'' in Africa.

I asked a Scottish teenager what her defining moment was and she said it was when Kate Winslet went down with the Titanic, thus joining the hand of history to the fingers of myth.

We all have our favourites and mine is a couple of hours on Christmas Eve 1914 somewhere in France.

Who started the truce and stopped the First World War, I just don't know. I think it was the British side made up of freezing and very frightened Tommies and Jocks.

They put down their guns, opened up their Christmas rations, lit up their cigarettes and produced a football which they proceeded to kick around in a muddy jigsaw of trenches called No-Man's Land. Later, they sang Silent Night. A few moments more, Germans came over to them with brandy and sausages. They sang Stille Nacht, Heilige Nacht.

The war stopped.

When officers reported what had happened, outraged generals, taking their orders from even more outraged politicians in London and Berlin, opened fire. They said that if the men didn't get back to killing one another, they'd be shot.

The war resumed.

The failure of that truce shaped what came later - the fall of the German

kaiser and the Russian tsar; the rise of Lenin; the rise of Hitler; the Second World War; the collapse of the British Empire; the Cold War; imperial responsibilities; and, later on, power passing into the hands of Washington's Pentagon and the White House; Vietnam; the collapse of Communism; the fall of the Berlin Wall in 1989.

The schoolgirl's choice is just as

good. The night of April 15, 1912, a 43,500-ton steamship, largest in the world, passengers neatly divided.

Then that unfortunate iceberg.

History deals with those events and personalities which have large and dramatic effects on lives and imaginations, wrote historial Robert Skidelsky. ''That is why so much of history is about war and revolution. That explains the concentration of acts of government and great people. When what kings and queens did had important effects, their actions held the centre of the stage. In any history of twentieth-century Britain, our royal family will get little attention. It has virtually ceased to be historical.''

l Word of the Century: the herald magazine ran a competition last March, in conjunction with HarperCollins, to find the defining word of the century. Television emerged as the word most voted by readers; our Word of the Week columnist Betty Kirkpatrick voted for technology