Battle of Aspern-Essling

On 21 and 22 May 1809 Napoleon tried to cross the Danube by way of Lobau island to reach the army of Archduke Charles, gathered on the left bank. On the Marchfeld plain the French clung to the villages of Aspern and Essling against a much larger Austrian army, while their pontoon bridges, battered by the flood and by objects floated downstream, gave way several times. Cut off from reinforcements and ammunition, Napoleon pulled his army back onto Lobau. The battle is regarded as Napoleon's first personal defeat in a major battle; Marshal Lannes was mortally wounded there.

On 10 April 1809 the army of Archduke Charles crossed into Bavaria, France's ally, without a declaration of war: seeing Napoleon bogged down in Spain, Austria wanted to wipe out Austerlitz and the Treaty of Pressburg. Caught off guard at first, the French won at Abensberg, Landshut, Eckmühl and Ratisbon; the Archduke withdrew north of the Danube and Napoleon entered Vienna on 13 May. With the bridges destroyed, the Austrian army regrouped on the left bank around the Bisamberg. A first crossing attempt by way of Schwarze Lackenau island, upstream of the city, was repulsed. Napoleon fell back on Lobau, downstream: a large wooded island, it hid the preparations, and the arm separating it from the Austrian bank was only about 150 metres wide. On the night of 19–20 May the French threw pontoon bridges across the main arm, then a last bridge to the left bank; Masséna's corps crossed and drove in the outposts. The Archduke let them come: he meant to strike whatever part of the army had crossed before the rest could come to its aid.

On 21 May the French formed up with their backs to the bridges, their left in Aspern and their right in Essling, two villages close to the river that could not be outflanked; Bessières's cavalry held the gap between them. The Archduke attacked in five columns: Hiller, Bellegarde and Hohenzollern against Aspern and Rosenberg against Essling. At Aspern, Molitor's division, reinforced by Legrand and Carra Saint-Cyr, defended a village that changed hands several times; by nightfall the Austrians held only part of it. At Essling, Lannes and Boudet's division threw back three successive assaults, relying on the fortified granary. To relieve the infantry, the cuirassiers charged the Austrian artillery; General Espagne was fatally struck. The bridge to the left bank broke a first time, but Lannes's corps (Saint-Hilaire's division and Oudinot's grenadiers) crossed during the night. At dawn on the 22nd Masséna retook Aspern and Essling held out. Napoleon then sent Lannes against the Austrian centre; the line wavered, but the Archduke committed his reserve grenadiers and led his men in person, a colour in his hand. Napoleon learned that the main bridge had failed again, carried away by boats and a floating mill released downstream: Davout's corps was stranded on the right bank and ammunition was running out. He called off the attack and ordered a step-by-step withdrawal. Aspern was lost; Essling, almost taken by Rosenberg, was cleared by Mouton's Young Guard and Rapp's fusiliers. Saint-Hilaire was mortally wounded and Lannes hit in the legs by a cannonball. Covered by Masséna, the army recrossed to Lobau with its movable wounded; the last soldiers left the left bank on 23 May. The Archduke did not pursue.

Losses were heavy and are counted in many ways: from 19,700 (Roberts) to 26,700 men (Rothenberg) on the French side, from 20,000 (Gill, Roberts) to 25,000 (Bodart) on the Austrian side. Napoleon's bulletin admitted only 4,100 killed and wounded. Lannes, the first Marshal of the Empire killed in battle, died of his wounds on 31 May. For Austria the battle proved that the Emperor could be beaten, and its propaganda hoped to rouse the occupied countries. Yet both armies stayed roughly where they had been and the strategic situation did not change, hence the 'status quo' verdict of some authors. Masséna received the title of Prince of Essling. Entrenched on Lobau, Napoleon waited there for his reinforcements, then recrossed the Danube and won at Wagram on 5 and 6 July 1809.