The men strained to raise themselves up to their full height and Napoleon could not help smiling at their fearless and fierce sense of elan. He replaced his hat, wheeled his horse about and galloped back to his command post, just behind the centre of Desaix’s line. They did not have long to wait for the enemy column. With drums beating the pace the Austrians marched straight down the road from Marengo. They did not falter for an instant when they saw the French lines waiting for them before San Giuliano, no doubt taking them for little more than a rearguard left behind to delay the Austrians for as long as possible while the main body of the French army fled.

Desaix shook his head. ‘They’re in for a surprise.’

‘That they certainly are,’ Napoleon replied quietly. ‘Signal Marmont to open fire.’

A staff officer relayed the order to a signalman and the flag fluttered up, held aloft for a moment and then swept down. The artillery crews rose up from their places of concealment and hastily cleared away the straw and cut branches hiding their guns. An instant later the cannon roared into life, belching deadly cones of grapeshot into the leading units of the Austrian pursuit column. Gun after gun fired in a rolling cannonade. The leading companies of the white-uniformed enemy were shredded by grapeshot and as the bodies piled into bloody heaps along the road the column stalled. Shocked by the sudden hail of destruction, they stood and endured the slaughter for some minutes before a senior officer attempted to take control. Slowly, too slowly, the head of the column began to deploy to either side of the road, still under heavy fire from Marmont’s guns, which were being worked as swiftly as their crews could manage. The target was so big there was no need to aim carefully and the guns discharged their grapeshot the moment they were reloaded.

After twenty minutes of terrible carnage, the Austrians were still attempting to draw their men up in a battle line. Napoleon realised that this was the moment to strike the decisive blow.

‘Order Marmont to cease fire. Tell Desaix to charge home!’

‘Yes, sir,’ Berthier nodded.

As soon as the last of the guns fell silent, the leading battalions of Desaix’s men marched through the dense bank of smoke and emerged a short distance from the enemy. Napoleon watched as Desaix ordered his men to halt and volley fire, before they advanced to point-blank range and halted to reload and fire again. Volley after volley rang out from both sides, each one wreaking terrible carnage. As he watched Napoleon sensed that the impetus was quickly draining from the French attack. Unless the Austrians broke soon, he doubted that they ever would.