The circumstances which recalled Bonaparte to the banks of the Mincio were indeed serious. The Emperor Francis was determined at all costs to retain his hold on Italy by raising the siege of that fortress; and unless the French commander could speedily compass its fall, he had the prospect of fighting a greatly superior army while his rear was threatened by the garrison of Mantua. Austria was making unparalleled efforts to drive this presumptuous young general from a land which she regarded as her own political preserve. Military historians have always been puzzled to account for her persistent efforts in 1796-7 to re-conquer Lombardy. But, in truth, the reasons are diplomatic, not military, and need not be detailed here. Suffice it to say that, though the Hapsburg lands in Swabia were threatened by Moreau's Army of the Rhine, Francis determined at all costs to recover his Italian possessions. To this end the Emperor now replaced the luckless Beaulieu by General Würmser, who had gained some reputation in the Rhenish campaigns; and, detaching 25,000 men from his northern armies to strengthen his army on the Adige, he bade him carry the double-headed eagle of Austria victoriously into the plains of Italy. Though too late to relieve the citadel of Milan, he was to strain every nerve to relieve Mantua; and, since the latest reports represented the French as widely dispersed for the plunder of Central Italy, the Emperor indulged the highest hopes of Würmser's success.[56] Possibly this might have been attained had the Austrian Emperor and staff understood the absolute need of concentration in attacking a commander who had already demonstrated its supreme importance in warfare. Yet the difficulties of marching an army of 47,000 men through the narrow defile carved by the Adige through the Tyrolese Alps, and the wide extent of the French covering lines, led to the adoption of a plan which favoured rapidity at the expense of security. Würmser was to divide his forces for the difficult march southward from Tyrol into Italy. In defence of this arrangement much could be urged. To have cumbered the two roads, which run on either side of the Adige from Trient towards Mantua, with infantry, cavalry, artillery, and the countless camp-followers, animals, and wagons that follow an army, would have been fatal alike to speed of marching and to success in mountain warfare. Even in the campaign of 1866 the greatest commander of this generation carried out his maxim, "March in separate columns: unite for fighting." But Würmser and the Aulic Council[57] at Vienna neglected to insure that reunion for attack, on which von Moltke laid such stress in his Bohemian campaign. The Austrian forces in 1796 were divided by obstacles which could not quickly be crossed, namely, by Lake Garda and the lofty mountains which tower above the valley of the Adige. Assuredly the Imperialists were not nearly strong enough to run any risks. The official Austrian returns show that the