Siege of Mantua (1796–1797)
The Siege of Mantua began on the 4th of June 1796 and would not end until the 2nd of February 1797 , a grinding, eight-month ordeal that decided who would rule northern Italy. Napoleon Bonaparte, still a young general of division, had already driven Austrian forces out of northwest and north-central Italy. But Mantua was different. Mantua was a fortress ringed by lakes and marshes, connected to dry land only by causeways, part of the famous Quadrilateral of four fortresses alongside Legnago, Verona, and Peschiera. Taking it would require not one siege but four separate battles fought against four successive Austrian relief armies. The questions Mantua posed to both sides were sharp ones: Could the Austrians break through to rescue their garrison? Could Bonaparte hold a siege and fight off full armies at the same time? And what would the fall of the city ultimately cost both powers?
Mantua sits in the Po River basin in the Lombardy region of Italy, on the Mincio River, which by 1796 had formed a large lake on the city's north and east sides. The city connected to its fortified suburbs by causeways , Cittadella to the north, San Giorgio to the east. The Po lay 13 km to the south; Peschiera on Lake Garda stood 32 km north. Roads running northeast to Verona and Vicenza linked the city to the Austrian frontier.
The geography that made Mantua hard to storm also made it a deathtrap for its defenders. In the 18th century, the city was notoriously unhealthy during warm months. The nearby marshes and lakes bred malaria-carrying mosquitoes in large numbers, though no one understood the mechanism at the time. Austrian soldiers who entered the fortress expecting relief would instead find disease waiting for them alongside the French blockade.
For the Austrians marching from Trento to the north, three routes led down to the Po valley. One ran parallel to the Adige on Lake Garda's east side. A second went west of Lake Garda through Riva and Lake Idro. A third led east through Levico Terme and south along the Brenta River valley to Bassano del Grappa. Each of these corridors would eventually see fighting. Controlling both Trento and Bassano allowed an Austrian army to move troops through the mountains without French interference , a strategic fact that shaped every relief attempt that followed.
Feldmarschall Dagobert Sigmund von Wurmser launched the first relief at the end of July 1796, sending 49,000 men in three columns toward a French force of only 44,000. Bonaparte had assembled a siege train of 179 heavy guns, opened siege parallels on the 4th of June, and placed General of Division Jean-Mathieu-Philibert Serurier in command of operations. The Austrian garrison inside numbered 14,000 under Feldmarschall-Leutnant Canto d'Irles.
Wurmser pushed Masséna back and Feldmarschall-Leutnant Peter Vitus von Quosdanovich seized Brescia, forcing Bonaparte to lift the siege on the 1st of August. The French burned the gun carriages of their heavy cannon, which were too slow to move. The garrison retrieved the abandoned gun tubes and dragged them back inside the walls. French besiegers suffered 1,200 killed and wounded plus 898 captured to that point; the defenders lost 492 killed or dead of disease, 395 wounded, and 87 captured. Another 3,275 Austrian soldiers were on the sick list.
After Quosdanovich's column collapsed at Lonato on the 3rd of August and Wurmser lost the Battle of Castiglione on the 5th, the Austrians retreated north. Before withdrawing, Wurmser threw two brigades into the fortress and evacuated some sick men. The loss of his siege cannons meant Bonaparte could no longer breach the walls. He was reduced to blockade.
The second relief came in early September. Wurmser marched down the Brenta valley with the bulk of his army while 14,000 Austrians under Paul Davidovich held the upper Adige valley to the north. Bonaparte overwhelmed Davidovich at Rovereto on the 4th of September, then cut loose from his supply line and chased Wurmser south. After a hard defeat at Bassano on the 8th of September, Wurmser refused to retreat east. He fought his way into Mantua with 10,367 infantry and 2,856 cavalry. The garrison now held nearly 30,000 men. Within six weeks, 4,000 of them died from wounds or sickness.
Feldzeugmeister József Alvinczi opened the third attempt in early November 1796 with a 28,000-strong Friaul Corps advancing from the Piave River. Davidovich's Tyrol Corps, reinforced to 19,000 men, moved south from Trento simultaneously. Bonaparte set Vaubois with 10,500 men near Trento and Masséna with 9,500 at Bassano, while Augereau held Verona with 8,500.
The French plan came apart quickly. Davidovich routed Vaubois at Calliano on the 7th of November. The same day, Bonaparte attacked Alvinczi at the Second Battle of Bassano with 19,500 troops and was beaten. On the 12th of November at Caldiero, a French assault on the Austrians was repulsed again. Bonaparte's army was in serious trouble. He briefly considered retreating all the way to the Adda River.
Instead, he noticed that the Austrian generals were moving slowly despite their advantages. He pulled every spare soldier from Vaubois and Kilmaine, left only Macquard with 3,000 men facing Alvinczi at Verona, and sent Masséna and Augereau to cross the Adige south of the Austrian line and hit Alvinczi's left flank. The Battle of Arcole ran from the 15th to the 17th of November. After three days of fighting, the French forced Alvinczi to withdraw east. Bonaparte then turned on the Tyrol Corps and sent it retreating north.
The cost was enormous. One source estimated the Arcole campaign cost the Austrians 17,832 casualties while French losses reached approximately 19,500. Inside Mantua, Wurmser tried to break out on the 23rd of November, losing 789 men and capturing 200 Frenchmen. When prisoners told him that Davidovich's corps had been routed, he abandoned the attempt and withdrew back inside the walls.
For the fourth relief, Alvinczi massed his main body of 28,000 in the north while sending Feldmarschall-Leutnant Giovanni Marchese di Provera with 9,000 soldiers and a bridging train from Padua to cross the Adige near Legnago and enter Mantua directly. A third column of 6,200 under Feldmarschall-Leutnant Adam Bajalics von Bajahaza would move southeast from Bassano and threaten Verona.
On the afternoon of the 13th of January 1797, Bonaparte realized the main Austrian blow was coming from the north. He ordered Masséna, Rey, and Victor to march to reinforce Joubert's 10,300-man division at Rivoli. That night, Provera crossed the Adige above Legnago at Angiari and headed for Mantua, leaving 2,000 men as a bridge guard.
On the 14th of January, Bonaparte crushed Alvinczi at Rivoli. He then sent Masséna south the next day while Augereau captured Provera's bridge guard. On the 16th, Provera's advance guard failed to penetrate Sérurier's blockade. A breakout attempt by Wurmser was repelled at dawn. Surrounded by Masséna, Augereau, and Sérurier, and unable to reach the city, Provera surrendered at La Favorita with 6,000 men. Alvinczi's main body by that point had lost 4,000 killed and wounded and another 8,000 captured. French casualties at Rivoli totalled 3,200.
Wurmser held out two more weeks before surrendering on the 2nd of February 1797. During the entire siege, the Austrians reported 16,333 killed, wounded, or dead of disease. Historian David G. Chandler estimated that as many as 18,000 Austrians and 7,000 French died over the course of the operation.
Wurmser walked out of Mantua with his honor largely intact. In recognition of his stout defense, the old field marshal was freed along with his staff and given an escort of 700 soldiers and 6 cannon. The rest of the garrison marched out with the honors of war and was paroled on condition of not fighting against France until exchanged. Only 16,000 Austrians were fit enough to walk out under their own power. Canto d'Irles, who had commanded the original garrison, died shortly afterward, his health destroyed by the long siege. The fortress passed to French control along with 325 cannon; Bonaparte also recovered the 179 guns he had burned in August 1796.
The strategic consequences spread rapidly. Bonaparte moved to crush the army of the Papal States at Faenza, then launched a final offensive toward Vienna in March 1797. The Austrians, bled by four failed relief attempts, sued for peace.
Historian David G. Chandler captured the Austrian failure plainly: "Throughout the whole year, the lure of Mantua continued to exert a fatal attraction over the Austrian field forces and led them to one costly failure after another." He traced the structural flaw to a repeated tactical habit. In each of the four relief attempts, the Austrian high command divided their forces along divergent lines of advance, hoping to divert Bonaparte and fragment his army. Instead, as Chandler wrote, "they only laid their own forces open to defeat in detail, throwing away the chance of commanding a decisive numerical superiority on the critical battlefield." The pattern held across all four attempts, from Quosdanovich's column at Lonato to Provera's surrender at La Favorita on the 16th of January 1797.
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Common questions
How long did the Siege of Mantua last?
The siege lasted from the 4th of June 1796 to the 2nd of February 1797, a period of roughly eight months, with a short break when the French were forced to lift the siege during the first Austrian relief attempt.
Why was Mantua so difficult to capture by storm?
Mantua was nearly surrounded by water in 1796 , a large lake formed by the Mincio River bordered its north and east sides, and the city connected to its suburbs only by causeways. This made a direct assault very difficult. After the French lost their siege cannon in August 1796, Bonaparte was left with no option but to blockade the city rather than breach its walls.
How many times did Austria attempt to relieve Mantua?
Austria made four separate relief attempts. The first was led by Wurmser in late July 1796; the second by Wurmser again in early September 1796; the third by Alvinczi in November 1796, culminating at the Battle of Arcole; and the fourth by Alvinczi in January 1797, ending with the French victory at Rivoli.
What were the human costs of the siege?
The Austrians reported 16,333 killed, wounded, or dead of disease during the siege. Historian David G. Chandler estimated that as many as 18,000 Austrians and 7,000 French died in total over the course of the operation. When Wurmser surrendered, only 16,000 Austrians were fit enough to march out under their own power.
What happened to Wurmser after the surrender?
In recognition of his determined defense, Wurmser was freed along with his staff and given an escort of 700 soldiers and 6 cannon. The rest of the garrison marched out with the honors of war and was paroled on condition of not fighting against France until exchanged.
What strategic impact did the fall of Mantua have?
The fall of Mantua, together with the heavy losses Austria suffered during the four relief attempts, left Austria without the means to continue the fight in Italy. Bonaparte quickly moved to eliminate the Papal States army at Faenza, then launched a final offensive toward Vienna in March 1797. Austria sued for peace that year.