After his victories over the Austrians and their Allies in 1796, and having just ended a strategically brilliant and dangerous crossing of the Alps to surprise his enemies, an over confident Bonaparte spread his forces thinly in the Marengo campaign to prevent the Austrians from escaping. He did not however plan for any aggressive movement from the Austrians under the experienced, General Melas. This underestimation of the enemy almost cost him his army and the Marengo campaign as Melas launched an early-morning attack that Bonaparte initially dismissed as a ruse, but as his forces came under more pressure, he realised he was in a serious dilemma. Sending out riders to recall two corps he had sent earlier to flank the Austrians when they "retreated", Bonaparte then set about trying to hold off the vast enemy. After several hours of fighting and with no reserves, Bonaparte's position was weakening and the French line began to give way.
The French military commander however, was fortunate and two events occurred that swung the battle in his favour. Firstly, Melas made the decision to leave the field and left his troops under General Zach. Secondly, the extremely talented General Desaix had heard the cannons firing and had turned around his divisions. Arriving back at the field of Marengo he approached Bonaparte and said that while the battle was lost, there was still time to win another. Launching a counterattack closely supported by a wedge of cannon, Desaix's men threw themselves at the Austrians. The assault cost Desaix his life, but won the day against the Austrians who broke and fled leaving behind 14,000 casualties. The French suffered 7000. This could have been a very costly defeat for Bonaparte had it not been for Desaix using his own initiative, and it could also be said that Bonaparte was very lucky that events had swung to his benefit.
Ulm was not really a battle, but rather a victory of manoeuvre for Bonaparte. By manoeuvring his forces around the 40,000 Austrians in the city of Ulm and cutting their supply lines he forced General Mack into an unsustainable situation. The Austrian general tried twice to break through the encircling French, at Haslach and Elchingen, but failed to do so. With no Russian reinforcements nearby, Mack surrendered his 27,000 men. Austria was effectively out of the war. However, as Correlli and Barnett have pointed out, it may have been an entirely different outcome had General Mack decided to break out as Melas had done at Marengo, or if the Russians had tried to help Mack rather than retreat. Bonaparte may have faced the possibility of fighting an enemy at two fronts and this could have resulted in the defeat of his army. It may have been seen as pure luck by Barnett that the Russians had decided to retreat instead of facing the “Grande Armee”.
Regarded as Napoleon's greatest victory, Austerlitz was an outstanding trap that destroyed the Austro-Russian army opposing him. It can be argued that Austerlitz was the finest example of Bonaparte’s tactical strategy as, by tricking his opponents into thinking he was weaker than he actually was, and then calling in nearby reinforcements, Bonaparte initially met the combined Allied army of 85,400 men and with just 73,100 men. The French emperor deliberately abandoned a strong central position and left his right flank weak in order to lure the enemy to approach there. The Allies readily moved forward off the Pratzen Heights and this could be said to have been a fatal mistake as they had then weakened the centre of their army in order to try and defeat the French right. As the bulk of the Russian troops attacked, Marshal Davout's I and III Corps had covered 64 miles in 48 hours and arrived to strengthen the French line, thereby winning the battle. However, it can be said that the Russians should not have moved off the Pratzen Heights as it is a military advantage, but if the attack of Davout had concentrated at the wrong place/time, there is the possibility that the French could have been defeated instead of the Russians.
The battle of Jena began with the chance meeting of Marshal Lannes' corps with a Prussian force of 45,000 men under General Hohenloe. Bonaparte used the Central position to divide the Prussians and defeated them at Jena-Auerstadt (Bonaparte 75,000 beat 47,000 Prussians and Davout 26,000 beat 45,000). Jena cost Bonaparte some 5000 men, but the Prussians had a staggering 25,000 casualties. However, the battle could have easily swung the other way as the French had made serious mistakes that could have been extremely costly for them. Marshal Bernadotte took no part in the two battles saying that he had received no orders from Bonaparte and meanwhile, two Corps arrived late at Jena having got lost en route. This battle could have been disastrous for the French if the Prussians had a modern army as they could have easily taken full advantage of the French position and defeated them. Bonaparte was extremely lucky that his strategic plans went without a hitch and this could be due to Davout using his initiative to defeat the larger Prussian army after Bonaparte mistakenly sending him to fight the vast Prussian army.
Having succeeded in capturing his Austrian enemy's capital of Vienna on 13 May, Napoleon Bonaparte needed to cross the Danube to seek out and destroy Archduke Charles and his main army. The emperor's problem centred on the successful destruction of bridges across the rain-swollen Danube by the retreating Austrians and he finally found a potential crossing point at Lobau Island, some four miles away. The island was occupied and a bridge constructed by engineers. On 20 May, Marshal Massena led his IV Corps across to form a bridgehead and to check for enemy troops. By the next morning, more than 24,000 men were occupying the villages of Aspern and Essling. The first thing the French command knew about the Austrian army was when more than 95,000 troops, supported by 200 cannon, moved against them. This lack of intelligence was a serious blunder on the French part as Bonaparte had underestimated his new opposition by not locating them before crossing the River Danube. Fortunately, for the French, a low wall ran between the two village strong points and this, together with desperate courage, allowed them to hold strong until they could figure out a way of getting out of this mess.
Driven out on several occasions, the French soldiers always managed to retake them at the point of a bayonet. By the 22 May, most of Bonaparte's forces were on the northern bank but the destruction of the bridge delayed Marshal Davout's III Corps and weakened a French counterattack that pushed the Austrians to breaking point. Knowing he did not have enough men to break the enemy, Bonaparte had ordered a withdrawal to the Aspern-Essling line where a renewed series of Austrian attacks forced him to pull back on to Lobau Island. While not a true defeat, Aspern-Essling marked the first serious turn around suffered by Bonaparte at the hands of his enemy. Archduke Charles made the mistake of believing that Bonaparte was really interested in peace with the Austrians – in fact, it was a ploy to build time for the French to build-up their strength and attack the Austrian force again.
“You engage, and then you wait and see” – so Napoleon Bonaparte considered his ability of war. He was described as a scrambler who never had a plan, strategic or tactical, that did not break down or change of necessity in the field. He was so confident of his ability to improvise, cover his own mistakes, and capitalize on those of the enemies that he repeatedly plunged his armies into uncertain, seemingly desperate situations, only to emerge victorious, "blundering to glory". However, it can also be said that there were Allied errors made as well as errors made on the French side; and that as mistakes were made, the French had also learned from them (e.g. in the battle of Aspern-Essling). The biggest factor, especially from the viewpoint of Connelly, was the element of risk involved in Bonaparte’s military campaign. If an enemy had adapted to his idea of Guibertian warfare or fought with a substantial military force, Bonaparte could have been forced to change his tactics and, could possibly have been defeated. Therefore, it may have been a combination of luck, through Allied mistakes, the strict discipline of the “Grande Armee” and the exceptional military command displayed by Bonaparte that helped in his campaigns during the “years of legend”.