The square staggered on, coming in range of the Austrian skirmishers, who added their fire to the cannon. MacDonald had already lost half his men, Napoleon estimated, yet still they advanced into the teeth of the enemy’s cannon and muskets. At last the survivors were close enough to the enemy line to fire their first volley in reply. The leading battalions deployed, loaded and raised their muskets, and fired at the nearest enemy guns and infantry formations. Napoleon felt a moment of blissful vengeance as the distant figures of Austrian artillerymen were cut down beside their guns.

MacDonald ordered the square to advance again and it pressed on, pausing to fire another volley before bayonets were fixed and they charged into the line of Austrian infantry waiting beyond.

The terrible tension of waiting for the division to get into action gave way to anxiety that MacDonald’s men had suffered too many casualties to carry the day. Napoleon nodded to himself as he made a decision.‘Berthier, we need every available man to support MacDonald! We must send forward what is left of Eugène’s reserves, and also the Imperial Guard.’

Berthier raised his eyebrows. ‘But sire, then we will have no reserves left. Nothing to face Archduke John should he reach the field.’

Napoleon gestured towards the two battalions assigned to guard the headquarters. ‘That will be our reserve. Send them to cover our right, and order the rest forward to save MacDonald, before it is too late.’

As the reinforcements swiftly advanced over the torn-up plain, Napoleon read through the latest reports from the other sectors of the battlefield. Davout and Masséna were driving back the Austrian flanks and Wagram had been taken by Prince Eugène and his men. Satisfied that the battle was tilting in his favour, he turned his attention back to the centre. With the aid of the fresh troops Napoleon had sent him, MacDonald was pushing steadily through the Austrian centre. Both sides were exchanging volleys at point-blank range and bodies lay in heaps across the battlefield. The arrival of the Imperial Guard proved to be decisive. After delivering one volley, they charged the Austrian line. There was a brief and bitter struggle and then the enemy broke, thousands of their men scrambling away towards the shelter of the hills running along the edge of the plain to the north.

At long last the Austrian army had been broken in two.