To Cross a River

To cross a river in the face of enemy resistance is a tricky operation. But Napoleon appreciated that the elusive campaign-ending victory required such a crossing. He believed he could not linger because he was at the end of a tenuous line of communications with an enemy to the front (Karl), flank (Erzherzog Johann in Italy and the rebellious Tyrolese in the mountains of upper Austria), and rear (England). Therefore, he had to come to grips soon with his main adversary and this required a combat crossing of the mighty Danube.

The crossing came in stages. First, on the night of 18 May French light infantry (voltigeurs) rowed across the Danube's main branch carrying a cable that would support the bridge to the island of Lobau. In Napoleon's mind, the island would serve as a staging area, a place of arms, for his entire offensive. While the voltigeurs performed this duty, pontonniers and a detachment of Imperial Guard Marines in small boats probed the river bottom with poles in order to locate places to anchor the pontoon bridge. After the voltigeurs cleared the island, construction began, carefully supervised by the Emperor himself.

When finally completed late the next night, the painstakingly built bridge spanned an 825-yard wide channel and was built atop 68 assorted fishing boats and 9 rafts. Because there were not enough anchors, workers sank open boxes filled with stones, cannonballs, and crates of canister. They even tied obsolete cannon barrels taken from Vienna's armory to the bridge to try to secure it against the Danube's fast-flowing current. By noon on 20 May the first bridge was complete and French soldiers began filing across to Lobau.

Lobau itself was a large, wooded island bisected by many small drainage canals. On Lobau Napoleon could mass his forces while remaining hidden from enemy eyes. The next challenge was to cross the 100-yard wide channel separating Lobau from the Austrian-held left [north] bank. Napoleon chose a place where the island formed a re-entrant angle to build a second bridge leading to the far bank. This position permitted French artillery to dominate the area that would become the tete de pont (bridgehead).

By 6 P.M. pontonniers had completed the second bridge. It barely reached to the far shore and it too was a rickety structure, being precariously supported on three trestles and 15 captured pontoons that had been especially reserved for an important task. The lack of time and materials prevented the construction of an upstream barrier to deflect objects propelled by the current. As soon as the pontonniers completed the second bridge, Molitor's infantry division crossed over to the tete de pont and began digging an earthwork to defend the position. Had anyone taken the time to notice, he would have seen that although the Danube was swollen and flowing fast, it was still well below previous flood marks.

Aspern: The Dawn of Battle

Napoleon rose before dawn on 21 May and, accompanied by his staff, rode to the right bank. Immediately his trained eye detected a flaw in the fortifications protecting the crossing site and he paused to trace a new line complete with an earthen lunette. This precaution was to prove very useful in the coming battle. He proceeded on and met with his principal lieutenants. The question of the moment was whether Karl would offer battle.

The Emperor coursed the field behind his outposts in order to learn the lay of the land. The French bridgehead debouched into a thin band of woods on the fringe of which he had designed the protective earth-works. Beyond the trees was a small plain extending to the villages of Aspern on the left and Essling on the right. In Napoleon's mind the position was like an entrenched camp, with Aspern on the left and Essling on the right serving as bastions, and the connecting elevated and ditched road, 2,000 yards long, acting like a curtain to unite the whole.

Aspern, a large village of some 1,500 inhabitants, was 2,000 yards from the bridges, Essling 3,000 yards distant. Both villages contained numerous stoutly constructed buildings surrounded by a network of small dikes designed to keep at bay the Danube floodwaters. Another 2,000 yards to the right of Essling was the village of Enzersdorf, which, in turn, was 600 yards from the Danube. The combination of villages and the elevated road provided a good defensive position. It was most vulnerable to attacks from the wings, but difficult, marshy terrain partially protected the area between Aspern and the Danube on the left flank, while an enemy advancing against the right flank between Essling and the river would confront flanking fire from Enzersdorf.

Napoleon was less interested in his means of defense than in what stood beyond his bridgehead out on the Marchfeld. For it was here that he intended to fight any battle. The Marchfeld was remarkably flat, rising only slightly to the north in the direction of Raasdorf and Breitenlee. It well-lent itself to ricochet fire, the tactic preferred by artillerists. Verdant fields of grain separated the small villages dotting the land. Napoleon could see that many of the villages contained substantial buildings, shining white in the gathering morning light. Nothing he saw during his reconnaissance discouraged him from the plan forming in his mind. He would debouch from his bridgehead onto the Marchfeld while refusing his left and leading with his right.

The Emperor Issues Orders

The Emperor issued a flurry of orders: Lannes would cross the bridge behind Massena, followed by Davout, the cuirassiers, the Guard, and the trains. It quickly became apparent that implementing these orders was going to require more time than anticipated. The fragile pontoon bridges, rocked by the Danube's fast flowing currents, forced all who crossed to proceed cautiously. Moreover, the river had risen three feet overnight. At 10 A.M., a heavily laden boat crashed through the second bridge. Like an opening gate, the two bridge sections separated as the water forced them apart. The French army stood riven in two. Until nearly evening, Massena's three divisions, numbering some 20,603 soldiers, supported by 8,554 troopers belonging to Marulaz's and Lasalle's light cavalry, Espagne's cuirassiers, and Nansouty's first brigade, and 58 cannon would have to stand alone.

Hussar trumpeter Phillippe Girault had crossed to the tete de pont shortly before the bridge behind him broke. He happened to come across Napoleon and his staff. He saw Marshal Berthier gesture toward the Marchfeld and say, "Here is a magnificent ballroom. We will make the Austrians dance!" Girault afterwards noted that this time the marshal was mistaken, "They made us dance, and we had to pay the violinist."

Karl's Plan

Erzherzog Karl had assembled his forces on the commanding Bisamberg heights on 18 May. The Bisamberg overlooked the old, well-used Hapsburg drill ground known as the Marchfeld. It was historic ground. Here, in 1277 Rudolph of Hapsburg had defeated the King of Bohemia. The next day Karl's lookouts reported the French concentration opposite Lobau.

On the morning of the 20th, Karl ordered a reconnaissance in force to verify the French intent to cross. In mid-afternoon, once he became convinced that the Lobau crossing was Napoleon's main effort, Karl shifted his army onto the slopes overlooking the Marchfeld. Massena had seen these men's campfires in the early hours of 21 May.

Karl then issued an eve of battle proclamation to his army: "Tomorrow, or the following day, there will be a great battle. The result of it will...decide the fate of the monarchy and the freedom of every one of you. Between eternal disgrace on the one hand, and undying fame on the other, there is no middle way. I count on the bravery of the army, on the example and spirit of enterprise of the officers."

As had been the case in 1277, the fate of Vienna and the Hapsburg dynasty would be determined on the Marchfeld. Because the Austrians had held periodic army maneuvers on this field, Karl and his staff knew the ground well. Yet, the lingering inefficiency that characterized Austrian staff work showed itself again when Karl requested a map of the battlefield. After considerable fumbling a breathless staff officer raced up with a map. Karl unfolded it only to see it was for an entirely different region!

On the night of 20-21 May, the Hapsburg Generalissimus drew up his battle plan. Karl divided his army into five attack columns, a cavalry corps, and a reserve of grenadiers. The French position described a shallow arc with the left, anchored on Aspern, lying closer to the Austrian overnight encampment. At precisely noon the movement would begin with the infantry marching by "demi-division" with each column having "a proper advance guard." The First Column, composing Hiller's VI Corps, would march to the Danube, deploy with its right flank solidly resting on the river, and advance through Stadlau toward Aspern "with all possible vigor." Hiller was to use his artillery to counter any French guns located on Lobau that interfered with this maneuver. The Second Column, Bellegarde's I Corps accompanied by Karl himself, would maintain contact with Hiller, march to Hirschstatten where it would join with the Third Column (Hohenzollern's II Corps) and jointly proceed toward Aspern. The Fourth Column, with half of Rosenberg's IV Corps) would move by Aderklaa and Raasdorf toward Essling. The Fifth Column, with the balance of Rosenberg's Corps, would pass east of Raasdorf, pivot on Enzersdorf and advance on Essling from the east. The grenadiers remained in distant reserve behind Gerasdorf while the cavalry screened the Third and Fourth Columns from any French cavalry charges.

This entire array composed about 70,000 infantry distributed among 103 infantry battalions, 12,000 cavalry distributed among 148 cavalry squadrons, and 288 artillery pieces divided into 42 batteries. Their objective was to throw the French back onto Lobau, destroy the bridge, and then line the Danube with numerous artillery, particularly howitzers, and pummel the enemy. Karl conceived of a series of feint crossings upstream to hold as many French as possible in place.

Flaws in the Austrian Plan

In sum, Karl's orders specified a ponderous attack order wholly characteristic of the Austrian way of war. In their first encounters in 1796 against a young general named Bonaparte, the Austrians had frittered away their numerical advantage by devising an overly complex attack plan composing numerous columns and detachments. So it had been on the eve of Austerlitz in 1805, when an Austrian staff officer had dictated an unwieldy allied plan of attack involving no less than seven major groupings. And so it was in 1809: another complex maneuver contrary, in Napoleon's words, "to the true principles of war."

There were two other flaws. The attack began in the afternoon. Even though it would remain light until close to 11 P.M., this reduced the time available to exploit any success. The plan also committed an undue strength directly against Aspern while ignoring the less easily defended ground between the two villages. Although Aspern was the key to the battle, the space required for troops to deploy meant that only a portion of the Austrian might could assault at any one time.

Part II: The Battle for Aspern Begins
Part III: Austrian General Assault

More About Aspern

Sidebar: The Good and Bad at Aspern
Scenario: French Defense of Aspern Order of Battle (text only--fast).
Scenario: French Defense of Aspern Order of Battle (graphics--very, very slow). Do not attempt to download unless you are on an ISDN or T-1 line.
Map: French Defense of Aspern
Diorama: French Defense of Aspern: photos of museum-quality diorama of the attack (slow).

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