The situation of the French Emperor was imminently hazardous; he was separated from Davoust and his reserves, and, had the enemy either attacked him in the islands, or passed the river higher up and so overwhelmed Davoust and relieved Vienna, the results might have been fatal. But the Archduke's loss in these two days had been very great; and, in place of risking an offensive movement, he contented himself with strengthening the position of Asperne and Essling, and awaiting quietly the moment when his enemy should choose to attempt once more the passage to the left bank, and the reoccupation of these stubbornly contested villages.
Napoleon availed himself of this pause with his usual skill. That he had been checked was true, and that the news would be heard with enthusiasm, he well knew. It was necessary, therefore, to regain the fame which had surrounded the beginning of the campaign, and he made every preparation for another decisive battle. Some weeks elapsed ere he ventured to assume the offensive.
On the 4th of July, 1809, Napoleon at last re-established his communication with the right bank, and arranged the means of passing to the left at a point where the Archduke had made hardly any preparation for receiving him. On the 5th of July, at 10 o'clock at night, the French began to cross from the islands in the Danube to the left bank. Gunboats prepared for the purpose silenced some of the Austrian batteries; others were avoided by passing the river out of reach of their fire on bridges that had been secretly erected by the French. When Napoleon had a river to be crossed he began the operation by suddenly conveying some determined men to the opposite side in boats. These proceeded to disarm or kill the enemy's advanced posts, and to fix the moorings to which the boats were to be attached that were to carry the bridge. The army then passed over as quickly as possible.
The first of these operations was the most difficult in presence of an enemy so numerous and so well prepared as were the Austrians. To facilitate it, Napoleon had large flat boats constructed, capable of carrying 300 men each, and having a moving gunwale to protect the men from musketry, which on being let down, would serve instead of planks for landing. Every corps was provided with five of these flat-boats, which made an advance guard of 1500 men carried over at once, and the enemy, not knowing exactly where the crossing would be made, could not confront the French with advanced posts in sufficient numbers to prevent their landing.
The Austrians having rashly calculated that Asperne and Essling must needs be the object of the next contest, as of the preceding, they were taken almost unawares by Napoleon's appearance in another quarter. They changed their line on the instant and occupied a position, the centre and key of which was the little town of Wagram. Here, on the 6th of July, the final and decisive battle was to be fought. Adding together the troops of Massena, Oudinot, Davoust, Bernadotte, Prince Eugene, Macdonald, Marmont, de Wrede and the Guard, there appeared to be 150,000 men; of whom 26,000 were cavalry and 12,000 artillerymen serving 550 guns; an enormous force, such as Napoleon had never yet mustered on a field of battle, and according to some authorities, such a host as had never been brought into action by any leader. Besides this vast force Napoleon had with him the invincible Massena, who was then suffering from a fall from his horse, but who was capable of mastering all physical sufferings on a day of battle; the stubborn Davoust, the impetuous Oudinot, the intrepid Macdonald, and a multitude of others who were ready to purchase the triumph of the French arms with their blood. The heroic Lannes was the only one missing. Fate had forbidden him to witness a victory to which he had powerfully contributed by his conduct in this campaign.
When the day dawned on the banks of the river, about 4 o'clock in the morning, a most imposing spectacle presented itself to both armies. The sun glistened on thousands of bayonets and helmets, and seventy thousand men were already in line of battle on the enemy's side of the river capable of making a good fight with the Archduke's forces. Seeing Napoleon ride along the front of the lines his soldiers raised their shakos on their bayonets and cried: "Vive l'Empereur!" The ground covered by the two armies was about two leagues in extent. The troops nearest were about 1200 fathoms from the city of Vienna, so that the towers, steeples, and tops of the highest houses, were covered by the numerous population, thus become spectators of the terrible contest then preparing.
The Archduke had extended his line over too wide a space, and his former error enabled Napoleon to at once see an opportunity to ruin him by his old device of pouring the full shock of his strength on the centre. In fact, so apparently weak was the position of the Austrians at this time that the Emperor, in his bulletin of the engagement sent to Paris, had this to say: "This disposition of the army appeared so absurd that some snare was dreaded, and the Emperor hesitated some time before ordering the easy dispositions which he had to make in order to annul those of the enemy, and render them fatal to him." At sunrise the cannonade commenced upon the two lines. Napoleon, perceiving that the Prince of Rosemberg was moving upon Marshal Davoust, repaired in person to the right wing, which he reinforced with the cuirassiers under General Arrighe, and caused twelve pieces of light artillery to advance upon the flank of the enemy's columns. After an obstinate engagement of two hours' duration, Davoust succeeded in repulsing his adversary as far as Neusiedel.
While the French army thus signalized itself by success in the beginning of the day, the battle was carried along the rest of the line with great determination. The fire of musketry and cannon was now general on that vast front of nearly three leagues, along which 300,000 men and 1100 pieces of cannon were arrayed against each other. It was a principle of Napoleon's that by concentrating on one point the action of certain special arms that grand effects were to be produced, and therefore it was that he bestowed an immense amount of artillery on the Guard and had kept under his hand a reserve of fourteen regiments of cuirassiers.
The Emperor now ordered that the whole of the artillery of the Guard, together with all that could be spared by the several corps, advance at a gallop. Just then General de Wrede arrived on the ground with twenty-five pieces of excellent artillery, and solicited the honor of taking part in the decisive movement, to which Napoleon consented. He then sent for General Macdonald, his design being to shake the Austrian centre with 100 guns, and then pierce it with Macdonald's bayonets and Nansouty's sabres. These orders were obeyed on the instant.
While awaiting the carrying out of these movements, impatient for the arrival of Macdonald and Lauriston, Napoleon rode about the field on his Persian horse of dazzling whiteness, giving orders to his aides constantly. The cannonading had by this time acquired the frequency of musket-firing, and everybody shuddered at the thought of seeing the man, on whose life so many destinies depended, struck by one of those blind messengers of death. The hundred guns were now ranged in line and instantly began the most tremendous slaughter ever known to those who witnessed it. Napoleon observed with his glass the effect of that formidable battery, saw the enemy's artillery dismounted, and was satisfied with the correctness of his own conceptions. But artillery was not sufficient to break the Austrian centre; bayonets, too, were requisite.