On some days, there were bright spells when brilliant white puffy clouds billowed serenely across a clear sky.Then there were times when thick banks of rain and mist blotted out the sun and icy squalls lashed down, soaking the men through to the skin and turning the routes along which they marched into glutinous slippery bogs. At night the temperature dropped swiftly and the men huddled around their campfires, trying to dry their clothes and get some warmth into their shivering frames as they supped on whatever food they had managed to forage during the afternoon. The lucky ones, mostly veterans who had long since learned the knack of finding good shelter, slept under cover, while the rest made themselves as comfortable as they could in the open. There were frequent frosts in the morning when the men woke to find their belongings covered in a gleaming patina of tiny ice crystals that gleamed pale blue in the hour before dawn. After a quick meal the men formed up, stamping their feet to keep warm, and then, when the order was given, they advanced towards the enemy again.

As his carriage lurched forward with the long train of headquarters wagons and mounted staff, Napoleon glanced through the streaked glass of the window and muttered to Berthier, ‘This mud may yet undo us.’

Berthier had been dozing, but he blinked his eyes open and looked round. ‘Sorry, sire, what did you say?’

‘This mud is slowing our advance down too much.’

‘It hampers the enemy as much as us, sire.’

‘True,’ Napoleon conceded. ‘But time is more against us than the enemy.We have to finish the war, swiftly and decisively.They only have to hold out long enough to demonstrate to the rest of Europe that France, that I, can be held at bay.’

Berthier nodded. ‘That is the danger, sire. But you have acted as quickly as you can.’ He paused for a moment to consider the disposition of his master’s forces.‘As long as Murat keeps pressing the Russians back they will have no chance to concentrate their forces with the Austrians.’

Napoleon smiled faintly. ‘I can’t say I feel terribly comforted by the thought of depending on a hothead like Murat.’

Berthier kept his silence. Not only was Murat senior to him, but he was also married to the sister of Napoleon, and any criticism of the impetuous cavalry commander was likely to be taken as a criticism of the Emperor’s family. Berthier knew that he was useful to Napoleon, but his position was not so secure that he dared to offer criticism of Marshal Murat. So he remained quiet and waited for Napoleon to continue.

‘We have to keep driving the enemy back towards Vienna,’ Napoleon said firmly. ‘If we can threaten their capital, then they will feel compelled to turn and fight us.’

‘What if they don’t, sire?’