‘Yes, sire.’ Masséna took his pencil from behind his ear and carefully noted the location on the folded map he was holding, then quickly tucked it away again before they attracted the attention of the Austrian sentries on the opposite bank, scarcely a hundred paces away. Napoleon and Masséna had borrowed the jackets and caps of two sergeants and set out without an escort in order not to provoke scrutiny of their reconnaissance work.

They were selecting the sites for the series of pontoon bridges that were to be thrown across the final stretch of the Danube. The first attempt to cross at the end of May had ended in a humiliating reverse that had cost thousands of lives, including that of Marshal Lannes. Napoleon’s enemies across Europe had been greatly encouraged by the news from Austria. The only way to retrieve the situation was to deliver a crushing blow against Archduke Charles and his army.

The difficulty was that the Danube separated Napoleon from his prey. In addition, the Austrian army had erected a formidable array of field fortifications in a wide arc that stretched across most of the bank that faced Lobau. The enemy had made no moves to carry the fight to Napoleon and seemed content to sit and wait for him.

With all Europe watching the conflict, Napoleon was determined to make another attempt to cross the river, and this time the result would be very different.

Every soldier that could be spared had been summoned to Vienna, where the army steadily increased in size until over a hundred and sixty thousand men had gathered to take part in the attack on Archduke Charles. The troops left to guard the army’s communications with France were thinly stretched and if only one more of the European powers chose to intervene on the side of Austria then there would be little to stand in their way.

Meanwhile Lobau was turned into a fortress. By the end of June over a hundred and thirty cannon were sited in batteries covering the far bank. Two strong bridges had been constructed across the main channel of the Danube as well as three new pontoon bridges. Stakes had been driven into the river bed upstream of the bridges to ensure that they would be protected from any Austrian fireships or floating rams. There was to be no dependence on a single, vulnerable bridge across the river this time.