“This battle is lost but there is still time yet to win another.”

It was 5pm on the 14^th June 1800 and Napoleon Bonaparte was on the brink of defeat in the vineyards and corn fields of the plain of Scrivia in northern Italy. But his faithful lieutenant, General Louis Desaix, mud splattered and sweating after a frantic ride cross-country, was undaunted, confident that victory could be snatched from the jaws of defeat.

The battle of Marengo, the climax of my novel Bitter Glory, had been underway for ten hours already. Lannes’ and Victor’s divisions had held the line unsupported against the bulk of the Austrian army for almost five hours before they were forced into a fighting retreat eastwards. As they withdrew, the Guard Infantry, sent forward to plug the gap between them had become isolated and had been cut to pieces by Austrian cavalry.

For hour after hour the dogged retreat continued. Though the French divisions held their discipline, Bonaparte knew that only the arrival of Desaix’s force could prevent a disaster. What he had expected to be a battle of annihilation, the total destruction of the Austrian army in front of Alessandria, was turning out to be the destruction of his own force.

Thinking to prevent the Austrians slipping away, Bonaparte had sent Desaix south to cut off any escape route there but the great man had been duped, partly due to false reports provided by a double agent in the service of the enemy. Desaix’s mission was a wild goose chase as the Austrians had no intention of trying to get away. Instead they launched their own attack and by 5pm they thought victory was theirs. Their commanding officer, Field Marshal Melas, with an injured hand, had withdrawn from the field, handing over to subordinates for the mopping up exercise.

Meanwhile, to the east, as Desaix’s men gradually arrived on the battlefield, a hastily improvised attack plan was put into action. Desaix attacked at the head of a fresh infantry brigade. Though he was killed by a shot in the chest almost immediately, his men pressed home the attack. The extended columns of the Austrian infantry were taken completely by surprise and then thrown into confusion and flight by a devastating charge by Kellerman, son of the hero of Valmy, at the head of his dragoons. His charge criss-crossed the Austrian columns creating havoc and when an ammunition carriage exploded behind the now panicked Austrians, they broke and fled.

This created a chain reaction of panic and rout in the Austrian army. They had been so convinced that victory was theirs that the sudden reverse was utterly devastating for them. Their morale collapsed. By 6.30pm they were in total retreat with thousands falling prisoner to the now rampant French forces.

When the fighting finally ended due to darkness and exhaustion at around 10pm the French forces were back to the positions they started in that morning and the battlefield was littered with thousands of dead and wounded.

Fifteen years later Wellington would famously describe Waterloo as a “damned close-run thing”, but there have been few battles in history that have seen a change of fortune so dramatic and so decisive as Marengo.