Winter had set in with a vengeance as they approached the mountains, which were shrouded in a thick layer of snow. A biting cold wind was blasting down from the north and made the going tough even before the column reached the bottom of the route leading up into the pass. There they camped for the night, taking advantage of any shelter from the wind that they could find in peasant hovels and behind low walls and rocky outcrops. The men huddled round fires that flared and roared as they were discovered by stray blasts of the wind. It was almost impossible to sleep in the icy cold of the night, and before dawn thick flakes were borne down on the howling wind to swirl around the shivering men and horses of the French army.

As dawn broke faintly across the bleak landscape the men shook themselves free of the snow and prepared to climb up the slope to the pass. Napoleon watched as the infantry formed up in long shivering columns and the artillery train harnessed their horses to the limbers and caissons.The men were silent and any attempt at levity in the ranks died away almost as soon as it began. The dragoons of the Imperial Guard were the first to advance up the slope. Both men and mounts lowered their heads into the wind that howled down from the pass as they trudged forward. Napoleon had ridden a little way ahead and watched as the dragoons passed by with hardly a sound. The thick snow had deadened the sound of their progress and fresh flurries added to the drifts that had formed across the narrow winding track.They advanced slowly, and eventually the tail of the column disappeared into the snowstorm, as the first of the infantry battalions made ready to follow.

In less than an hour a messenger arrived from the commander of the dragoons. His breath burst from his lips in ragged puffs that were instantly ripped away by the wind as he reported to the Emperor.

‘Sire, the colonel begs to inform you that his men can go no further. The colonel has halted to await orders.’

‘Await orders? The colonel has his orders! Tell him to keep moving. I will not have my army held up because the colonel can’t bear a little cold.’

The messenger bowed his head, and then looked up nervously.‘I beg your pardon, sire, but my colonel is right. It is not possible to advance any further.’

‘And why not?’ Napoleon asked tersely. ‘Explain.’