Mantua lies on an island, being cut off on all sides from the main land by the branches of the Mincio, and approachable only by five narrow causeways of which three were now defended by strong and regular fortresses or intrenched camps; the other two by gates, drawbridge and batteries. The garrison was prepared to maintain the position, was well-nigh impregnable and the occupants awaited the hour to discover whether Napoleon possessed any new system of attack capable of shortening the usual operations of a siege as effectually as he had already done by the march and the battle.
It was a matter of high importance that Napoleon should reduce this place quickly, for a large army under Field-Marshal Wurmser, one of the most able and experienced of the Austrian generals, was about to enter Italy. His commencement gave cause for much alarm to those within the fortress. Of the five causeways, by sudden and overwhelming assaults, he obtained four; the garrison was cut off from the main land except at the fifth causeway, the strongest of them all, named from a palace near it, "La Favorita." It seemed necessary, however, in order that this blockade might be complete, that the Venetian territory, lying immediately behind Mantua, should be occupied by the French, and the claim of neutrality was not allowed to interfere with Napoleon's plans.
"You are too weak," said Bonaparte, when a Venetian envoy reached his headquarters, "to enforce neutrality on hostile nations such as France and Austria. Beaulieu did not respect your territory when his interest bade him violate it; nor shall I hesitate to occupy whatever falls within the line of the Adige."
Garrisons were placed forthwith in Verona and all the strong places of that domain. Napoleon now returned to Milan to transact important business, leaving Serrurier and Vaubois to blockade Mantua.
The king of Naples, utterly confounded by the success of the French, was now anxious to secure peace on whatever terms proposed, and Bonaparte, knowing that it would result in a withdrawal of some valuable divisions from the army of Beaulieu, arranged an armistice which was soon followed by a formal peace, and the Neapolitan troops, abandoning the Austrian general, began their march to the south of Italy. This was followed by peace arrangements with the Pope of whom Napoleon demanded, and obtained, as a price of the brief respite from invasion, a million sterling, one hundred of the finest pictures and statues in the papal gallery, a large supply of military stores and the cession of Ancona, Ferrara and Bologna, with their respective domains. The siege of the citadel of Milan, rigorously pressed, was at length successful. The garrison capitulated on the 29th of June, and by the 18th of July, one hundred and forty pieces of cannon were before Mantua.
The French general had stripped Austria of all her Italian possessions except Mantua, and the tri-color was waving from the Tyrol to the Mediterranean. Napoleon was now, in effect, master of Italy. Future success seemed to him to be assured, although the French Directory was with difficulty persuaded to let him follow the course he had adopted for himself.
The cabinet of Vienna at last resolved upon sending stronger reinforcements to the Italian frontier, and Bonaparte was now recalled from Milan to the seat of war to defend himself against them. What the Austrian court now feared was that Napoleon, who had already annihilated her Italian army, and had wrested from her the Italian domains, would soon march into the heart of her Empire and dictate a peace under the walls of her capital. All Italy was now subdued or in alliance with the French Republic except Mantua.
Beaulieu, who had been so thoroughly routed by Napoleon, was to be no longer trusted. Finding himself incompetent to withstand a general "whose mistress was glory and whose companion was Plutarch" while traversing the Tyrol with the wrecks of his army, forwarded a letter to Vienna which fully displayed the irritated feelings of the veteran commander at this time. He said: "I hereby make known to you that I have only 20,000 men remaining, while the enemy's forces exceed 60,000. I further apprise you, that it is my intention to retreat to-morrow,—the next day—the day following—nay, every day,—even to Siberia, should they pursue me so far. My age accords me liberty to be thus explicit. Hasten to ratify peace, be the conditions what they may!" Wurmser, whose reputation was of the best, and who was older than Beaulieu but not less obstinate, was sent to replace him, and 30,000 men were drafted from the armies on the Rhine charged with restoring the fortunes of Austria beyond the Alps. Wurmser's orders, too, were to strengthen himself, on his march, by whatever recruits he could raise among the warlike and loyal population of the Tyrol.