On its lower course, where the river widens out into a semicircular lagoon flanked by marshes and backwaters, is the historic town of Mantua.

For this position, if we may trust the picturesque lines of Mantua's noblest son,[53] the three earliest races of Northern Italy had striven; and when the power of imperial Rome was waning, the fierce Attila pitched his camp on the banks of the Mincio, and there received the pontiff Leo, whose prayers and dignity averted the threatening torrent of the Scythian horse.
It was by this stream, famed in war as in song, that the Imperialists now halted their shattered forces, awaiting reinforcements from Tyrol.
These would pass down the valley of the Adige, and in the last part of their march would cross the lands of the Venetian Republic.

For this action there was a long-established right of way, which did not involve a breach of the neutrality of Venice.

But, as some of the Austrian troops had straggled on to the Venetian territory south of Brescia, the French commander had no hesitation in openly violating Venetian neutrality by the occupation of that town (May 26th).
Augereau's division was also ordered to push on towards the west shore of Lake Garda, and there collect boats as if a crossing were intended.
Seeing this, the Austrians seized the small Venetian fortress of Peschiera, which commands the exit of the Mincio from the lake, and Venetian neutrality was thenceforth wholly disregarded.
By adroit moves on the borders of the lake, Bonaparte now sought to make Beaulieu nervous about his communications with Tyrol through the river valley of the Adige; he completely succeeded: seeking to guard the important positions on that river between Rivoli and Roveredo, Beaulieu so weakened his forces on the Mincio, that at Borghetto and Valeggio he had only two battalions and ten squadrons of horse, or about two thousand men.

Lannes' grenadiers, therefore, had little difficulty in forcing a passage on May 30th, whereupon Beaulieu withdrew to the upper Adige, highly satisfied with himself for having victualled the fortress of Mantua so that it could withstand a long siege.