In Italy it is common to hear it said that it was necessary to station a large army on the Mincio to bar the Archduke's path to Milan. But apart from the rumoured existence of a promise to the French Emperor not to invade Lombardy, it was unlikely that so good a general as the Archduke would have taken his small army far from the security it enjoyed among the four fortresses which, if the worst came to the worst, assured him a safe line of retreat.
The plan adopted by La Marmora is vaguely said to have been that which was prepared by the French and Sardinian staffs for use in 1859, had the war been continued. But in what it really consisted is not to this day placed beyond dispute. The army, roughly speaking, was divided into halves; one (the larger) half under the King and La Marmora was to operate on the Mincio; the other, under Cialdini, was to operate on the lower Po. It is supposed that one of these portions was intended to act as a blind to deceive the enemy as to the movements of the other portion; the undecided question is, which was meant to be the principal and which the accessory?
The volunteers were thrown against the precipices of the Tridentine mountains, where a detachment of the regular army, well-armed and properly supplied with artillery, would have been better suited for the work. The Garibaldian headquarters was at Salò on the Lake of Garda. Less than half of the 35,000 volunteers who appear upon paper, were ever ready to be sent to the front. It was widely said that only patriotism prevented Garibaldi from throwing up his command, so dissatisfied was he with the conduct of affairs.
Prussia invaded Hanover and Saxony on the 16th of June, and declared war with Austria on the 21st, one day after the Italian declaration of war had been delivered to the Archduke Albrecht. On the 23rd La Marmora's army began to cross the Mincio. It consisted of three _corps d'armée_ under the command of Generals Durando, Cucchiari and Delia Rocca, each corps containing four divisions. The force under Cialdini was composed of eight divisions forming one _corps d'armée._ An Italian military writer rates the numbers at 133,000 and 82,000 respectively. La Marmora acquired the belief that the Archduke's attention was absorbed by Cialdini's movements on the Po, and that his own operations on the Mincio would pass unobserved.