Faulty as these dispositions were, they yet seriously disconcerted Bonaparte. He was at Montechiaro, a village situated on the road between Brescia and Mantua, when, on July 29th, he heard that the white-coats had driven in Masséna's vanguard above Rivoli on the Adige, were menacing other positions near Verona and Legnago, and were advancing on Brescia. As soon as the full extent of the peril was manifest, he sent off ten despatches to his generals, ordering a concentration of troops--these, of course, fighting so as to delay the pursuit--towards the southern end of Lake Garda. This wise step probably saved his isolated forces from disaster. It was at that point that the Austrians proposed to unite their two chief columns and crush the French detachments. But, by drawing in the divisions of Masséna and Augereau towards the Mincio, Bonaparte speedily assembled a formidable array, and held the central position between the eastern and western divisions of the Imperialists. He gave up the important defensive line of the Adige, it is true; but by promptly rallying on the Mincio, he occupied a base that was defended on the north by the small fortress of Peschiera and the waters of Lake Garda. Holding the bridges over the Mincio, he could strike at his assailants wherever they should attack; above all, he still covered the siege of Mantua. Such were his dispositions on July 29th and 30th. On the latter day he heard of the loss of Brescia, and the consequent cutting of his communications with Milan. Thereupon he promptly ordered Sérurier, who was besieging Mantua, to make a last vigorous effort to take that fortress, but also to assure his retreat westwards if fortune failed him. Later in the day he ordered him forthwith to send away his siege-train, throwing into the lake or burying whatever he could not save from the advancing Imperialists.
This apparently desperate step, which seemed to forebode the abandonment not only of the siege of Mantua, but of the whole of Lombardy, was in reality a masterstroke. Bonaparte had perceived the truth, which the campaigns of 1813 and 1870 were abundantly to illustrate--that the possession of fortresses, and consequently their siege by an invader, is of secondary importance when compared with a decisive victory gained in the open. When menaced by superior forces advancing towards the south of Lake Garda, he saw that he must sacrifice his siege works, even his siege-train, in order to gain for a few precious days that superiority in the field which the division of the Imperialist columns still left to him.