'The passage from the defensive to the offensive is one of the most delicate operations of war' - Napoleon
By January of 1809, the Austrians had again abandoned their treaty obligations and were preparing for war with France, and they would inaugurate the War of the Fifth Coalition with even more zeal than before. A war party had come to power in Austria in 1808, wanting to avenge the defeats of Ulm and Austerlitz. Encouraging news to the Austrians was all that trouble the French were running into in Spain, the transfer of troops stationed in Germany to Spain, and the fact that Napoleon himself was in Spain as well.
Noteworthy among the war hawks in Vienna were the Archdukes John and Ferdinand and the third wife of Francis I, Empress Maria Ludovica. Archduke Charles had recently introduced into the Austrian army a Corps organization modeled on the design employed by Napoleon within the Grand Army. Upon this foundation, Charles had built up an army of 300,000. Emperor Francis ended up giving him command of the main army of 209,000 while Archduke John marched on French-controlled Italy with 72,000 men. On April 9, Archduke Charles proclaimed a 'War of German Liberation' and marched into Bavaria, invading Napoleon's Confederation of the Rhine.
Napoleon, meanwhile, had called up conscripts from the Classes of 1809 and 1810. He also ordered Berthier to reorganize the 90,000 men of his Army of The Rhine. The War of the Fifth Coalition, then, started with a minor French victory at Abensberg on April 20, 1809. Napoleon then struck south of the Danube, directing his forces to Landshut thinking that the Austrians were there. By going south, however, Napoleon had left Davout's corps exposed near a place called Eckmuhl. Charles attacked Davout there on April 21, and Davout began sending the Emperor dispatches emphatically stating his belief that he he was facing the entire Austrian army.
Napoleon thought that Charles was merely retreating through Eckmuhl and would no doubt show up at Landshut during the evening of the 21st. Meanwhile, Davout was still sending Napoleon more and more dispatches begging for reinforcement. Finally, the Emperor sent four divisions up to help him out. Napoleon arrived at Eckmuhl on the afternoon of April 22, probably saving Davout from virtual destruction. Charles withdrew through the ancient fortress of Regensburg. He kept picking up scattered units and by the time he reached Vienna he had 100,000 men. On April 23 Napoleon decided not to lay siege to Ratisbon (modern-day Regensburg), but instead to scale its walls. He got so frustrated by the fact that his army was stalled by the merely 6,000 Austrians in the castle that he rode too close to the battle and he was hit by a stray musket ball in the right ankle. He was alright, however, as Dr. Larrey observed that the wound barely drew any blood.
Instead of following Archduke Charles, Napoleon decided to march on the capital of the Austrian Empire - Vienna herself, thinking that if he took Vienna the Austrians would sue for peace. But when he go there, on May 13 1809, he found that Francis I this time would not be so quick to offer peace as he had after Austerlitz. Napoleon needed to cross the Danube river in order to catch up with and engage Charles. He looked around and found the most plausible place to cross (as all of the bridges had been destroyed) was Lobau.
On May 20, the French finally completed the pontoon bridges across the Danube. On May 21 Charles unleashed his infantry and his cavalry against the French bridgehead between Aspern and Essling. Charles had 100,000 men and 260 guns at Aspern Essling, whereas the French only had 30,000 with about 75-80 guns. On the morning of May 22, Napoleon was present and brought up some more men (about 8,000 Imperial Guard). Those, with other reinforcements, brought the total French strength up to about 55,000 as of the morning of May 22. Napoleon didn't think that the whole Austrian army was in front of him, so he decided to attack it. Little did he know that he had just flung 55,000 men head long into an army nearly twice the size. Initially, the Austrians were taken off guard, still wary of the great Eagle. But soon the French ran low on ammunition and Charles grabbed the flag of the Zach regiment of his grenadiers and led them forward into French fire, a heroic act worthy of special mention.
Meanwhile, that morning the Austrians had cut loose a massive floating flour mill and sent it down the river, where it crashed into the pontoon bridges that had been built and destroyed them, isolating the troops on the bank. The Austrians closed in quickly. Massena lost the village of Aspern twice, but finally regained it and held it. On the French center, Austrian infantry attacks were stopped by Lannes' infantry. On the right, Essling finally fell about 2:00 PM, but Napoleon sent in four battalions of the Imperial Guard and promptly retook it. Charles finally pulled back, and began to destroy the French with artillery fire (he had 260 guns, to Napoleon's mere 75 guns). An hour later, Napoleon turned control over to Marshal Lannes and decided to go back to Lobau Island.
Just moments after Napoleon had left him in charge, a cannonball shattered the legs of Marshal Lannes. Napoleon's innovative Imperial Guard surgeon, Baron Dominique Larrey, amputated one of them. Lannes would die nine days later, and Napoleon openly mourned the loss of one of his oldest buddies. Napoleon wrote to his widow: 'I have lost the most distinguished general in my army, my companion in arms for sixteen years, and my best friend.' Interesting enough, Napoleon withdrew his army and proclaimed that the Danube, not the Austrians, had defeated him...which isn't far from the truth in this case. The Austrians believed they had won, and so celebrated that evening. Little did they know that reinforcements were already called up and on their way to the hard-pressed Emperor's rescue.
Archduke John, meanwhile, continued his march into Italy with 72,000 men, and of those he sent 10,000 into the Tyrol and another 12,000 into French controlled Dalmatia. On 16 April 1809 he defeated Eugene (commanding 35,000 French and Italians) at Sacile. Eugene promptly retreated past the Piave River. When John soon became aware of Napoleon's victories in Germany, he began to pull back over the Alps to help Charles.
Eugene chased him and inflicted terrible casualties when John crossed the Tagliamento and Piave rivers, actually chasing John all the way into Hungary! Eugene then decided to assign General Macdonald (about 16,000 men) to the task of keeping up the chase after John while Eugene himself disengaged and marched off quickly in the direction of Vienna to the assistance of his famous Father-in-Law, meeting up with Napoleon on May 27. Upon meeting Eugene, Napoleon had immediately increased his strength to 45,000 men and told him to stop John from meeting up with Charles.
John marched north along the Raab river in Hungary and expected to get some reinforcements from Raab itself. However, a minor insurrection by some nobles caused him to get very little, if any, help. On June 14, Eugene caught John off guard at Raab with his 35,000 troops, most of them still tired from the long march. John was able to make it across the Danube with 11,000 men but had to retreat southeast, away from Vienna...and his brother Charles. Eugene met up with Napoleon with about 30,000 men.
With reinforcements almost constantly arriving in bits and pieces, Napoleon by the end of June had a total of 190,000 men on Lobau island. Charles' forces had remained static at around 140,000 men. Charles had done something ingenious, however. He had placed 25,000 men on the old Aspern-Essling line, and there these forces were supposed to buy time for the main Austrian army (about 6 miles behind Charles) to move into position. Unfortunately, when the French landed this detachment of troops was quickly overrun. Charles kept hoping he would be reinforced by John. For his part, John eventually would reach Wagram, but too late to alter the decision. The other armies that could have helped Charles were engaged in battles with Jerome Bonaparte in and around Bohemia.
On the night of 4-5 July, in an operation brimming with ingenius planning and execution, Napoleon and all his forces recrossed the Danube from Lobau island during a horrendous thunderstorm. The French outflanked the Aspern-Essling line, and as its surprised defenders began evacuating the French troops poured across all the bridges. On July 6, Charles saw that the French were largely concentrated on his left, due East at Wagram. That morning, he sent General von Klenau's corps through the French cavalry screen on their (the French) left.
Charles's plan was to use General von Klenau to break through the French left, take down the bridges and hit the French rear as hard as he could. Kolowrat's corps was also to meet up with him, and hopefully resulting in a total envelopment. Charles planned to keep Napoleon occupied by bombarding the center of the French line, and then launching a huge assault on the center. The majority of the fighting focused on Bernadotte's Saxony corps who turned and ran. Napoleon by this time was thoroughly fed up with the envious and always untrustworthy Bernadotte, dismissing him from the field in disgrace.
Next, an amazing thing happened. Klenau had broken through where he was supposed to, yet he halted when he saw Massena in motion, noting also that Kolowrat was doing nothing. As the Austrians inexplicably paused, Massena literally swept them up, having the French troops charge in column and in line firing the whole time, then closing in with bayonets. He had stopped Charles supposed plan of an attack from the rear, and quite possibly saved the day for the French.
Meanwhile back at Napoleon's command post, he had a total of 37,500 troops stationed around him. As the fighting continued he sent Marmont's corps of 12,500 to reinforce Massena. His eagle's eye having noticed a gap opening in the Austrian center, Napoleon decided to exploit an obvious opportunity to force a decision and ordered up a massive cannonade on the Austrian center, bombarding it with a total of 102 guns, 72 of them under the command of the talented artillery General Drouot of the Imperial Guard. Arranged in a semicircle nearly a half mile long, this grand battery, the famed 'Hundred Guns of Wagram', mercilessly hammered away at the Austrians. Marshal Macdonald then went forward with 8,000 men from thirty battalions arranged into a gigantic battle square. Slowly, the Austrians slowly began to give ground, though their artillery caused about 4,500 casualties in Macdonald's decimated ranks.
The retreating Austrians soon rallied and began to charge forward when Napoleon sent up a division and a brigade of the Imperial Guard's cavalry to stop the bleeding. Eugene then took the town of Wagram on the right. Davout, meanwhile, had been doing his usual thing, rolling up the Austrians on the left all day long. In mid-afternoon the French were advancing all across their line. Later that day, Charles realized his brother Archduke John and his men had arrived to late to be of any help and ordered an organized retreat of his army north into Moravia.
Though his victory at Wagram was decisive and did indeed end the war, Napoleon realized that this had been no Austerlitz, and that to win many high ranking officers including Marshals and Generals alike, including the flamboyant horse soldier Antoine Lasalle who was killed in the battle, had to risk their lives in the line of fire to secure the victory. Nonetheless, he wrote to Josephine shortly after the battle saying that it was complete and added `I am sunburned.' Although Charles still had 80,000 men available, he had lost the heart to continue the fight after the unexpected disappointment of Wagram and asked for a truce on July 12, which was granted. Believing he had squandered a great opportunity to deal Napoleon his first serious check since Eylau, Charles retired from the Austrian army altogether.
Though Tyrolean partisans under the guerilla chief Andreas Hofer continued to be a thorn in the side of the French for some time after Wagram, back in Vienna Napoleon had once again taken up residence in Schonbrunn Palace and awaited the offers of peace. That would come 3 months later, in October of 1809, when Emperor Francis came to make peace. Napoleon this time punished Austria severely for her hubris by taking her Balkan territores, giving the Czar some of Austrian Galicia, giving the Duchy of Warsaw some of Galicia, giving his German allies some more of Austria and giving back the Tyrol to his Bavarian friends. It would be 4 more years before Austria would again post a threat to Napoleon.