Historical Notes: For want of a nail the battle was lost

WAR IS not about trumpets and military glory, war is about death. Or, to paraphrase Georges Clemenceau, the man who led France from the horror of the First World War: "War is much too important to be left to generals."

There are certain chroniclers who wish us to believe that battles are won by valour and the brilliance of warlords, on whom they bestow the accolade of "genius" when they are triumphant. These same chroniclers record the victor as being dazzling and the loser as not. And yet, there is no secret formula to the victorious outcome of a battle - except that much depends on who may have committed a bigger blunder. Or, to put it bluntly, many battles have been decided by the caprice of weather, bad (or good) intelligence, unexpected heroism or individual incompetence - in other words, the unpredictable. In military terms, this phenomenon is known as the Hinge Factor.

In the days of the classical battle, a fight would last a fair few hours before the victors slaughtered the underdogs. The knockout blows were delivered by a few thousand men and a hinge factor could often be clearly established.

The time was 4pm, the date 18 June 1815, the place Waterloo. "Vive l'Empereur!" was the cry from the French. The ground trembled from the pounding of 20,000 hooves of the French cavalry. Colonel Cornelius Frazer looked at the mass of riders coming up on both sides of the Brussels road and thought to himself: "They are going to roll over us." Quick as a flash, he ordered: "Form squares!" In minutes, the entire plateau of Mont St Jean was flooded with Marshal Ney's cuirassiers, wheeling madly around the British squares. If even just one of the British squares had given, Wellington would have been lost.

The squares held because only artillery could make infantry squares disintegrate. French guns couldn't fire without striking their own riders. But other guns were in place - the French had managed to capture the entire English artillery park during the mad ride. Colonel Heymes, Marshal Ney's aide, was at the artillery park when he heard the dull thunder of an approaching wave. It was Uxbridge's heavy cavalry approaching. Heymes had to act and act quickly in order to disable English artillery. "Les clous!" he yelled. "Nails! Spike the guns!" But not a single French rider had nails with which to spike the firing holes, and render the English artillery useless. A handful of nails to put these guns out of action, and nothing, not even the arrival of the Prussians, could have saved Wellington that day.

The Hinge Factor at Waterloo is almost too ironic. A handful of headless nails and a few hammers could have made a massive difference to the outcome of the battle. It is doubtful if Napoleon could have won the war of 1815, but he would have certainly carried Waterloo.

The decisive hinge aspect of both world wars was obscured by the duration of the drawn-out encounters - until their climactic finale in Japan. With that one bright flash the world eliminated the principle that "war is the ultimate instrument of policy".

Recorded history will always tell us what happened. But there is invariably a reason why something happened. I make no claim to present a coherent or definitive explanation why the outcome of any particular battle might take a particular turn. But, at the end of every conflict, it has become standard practice that politicians and generals justify their action in print, explain their moves across the chessboard of battle. The simple footsoldier writes home about the way he has lived through it. It is from both these records that I have selected my 17 Hinge Factors. From the stratagem of the Wooden Horse of Troy, to the Zero Factor of the Gulf War, had the hinge swung the other way, one may well ponder the historic consequences.

Erik Durschmied is the author of `The Hinge Factor: how chance and stupidity have changed history' (Hodder & Stoughton, pounds 14.99)