Again: it will be remembered that no sooner had Melas learned that the Army of Reserve was marching on Milan than he sent orders to General Elsnitz to abandon the Var and to General Ott to raise the siege of Genoa. Even the mere knowledge of Bonaparte's destination, before the movement on Milan had actually been completed, was of itself sufficient to cause Melas to change immediately his entire plan of campaign. Had not Masséna, at the time, been just on the point of giving up Genoa, General Ott would not have delayed there two or three days to await the capitulation. In fact, had Masséna known of the exact state of affairs, he doubtless would have held out a day or two longer, and saved himself the humiliation of a surrender. Even without a battle, the concentration of the French forces between Milan and Placentia would, in a short time, have set free Masséna's soldiers; for Melas would then have been obliged to concentrate and fight, in order to recover his communications and connect with his base of supplies. Bonaparte saw clearly this fact. Though he did not know how long Masséna could hold out at Genoa, he realized that matters there were rapidly approaching a crisis, and that it was of the utmost importance that the Army of Reserve should reach Milan at the earliest possible moment. He realized that upon the direction given his columns and upon the rapidity of their movements depended the fate of Suchet on the Var and of Masséna at Genoa.
Other reasons, too, deterred Bonaparte from marching the Army of Reserve through Switzerland. In this rough and mountainous country, supplies could not be easily obtained. Especially was this true of the St. Gothard route, which had been overrun by the French during the two previous years. Besides, this route was reserved for Moncey's corps, which, of itself, would tax to the utmost the resources of the country. Moreover, this road, a mere bridle path in places, passes through narrow defiles and across lofty and rugged mountains. Evidently a large army issuing into Italy by this route would be so stretched out that the advance divisions could be defeated before the rear divisions could re-enforce them.
The Simplon route was shorter than the St. Gothard route, but the difficulties to be overcome on each were of the same character. Inasmuch, however, as Lake Maggiore lies between these two routes, it will be observed that, had Bonaparte advanced into Italy by way of the Simplon, while Moncey marched by way of the St. Gothard, Melas might have assembled a strong force at the foot of the lake, and, from his central position, have thrown superior numbers against each French column in succession. In this way he might have defeated both in detail before they could have united at Milan.
The principal reasons why Bonaparte chose the Great St. Bernard route having been considered, it will now be of interest to point out the several courses that he might have taken after having descended the Alps into the lower valley of the Aosta. It will be remembered that on the 27th of May Bonaparte was between Ivrea and Chivasso with thirty-five thousand men, and that Melas was at Turin with sixteen or seventeen thousand. At this time Bonaparte might have taken any one of three courses. He might have advanced on Turin, driven back Melas, united with Thurreau's division at Susa, and thus have secured his communications with France by the Mont Cenis route; or he might have crossed the Po at Chivasso, attacked and driven Melas from Turin, then have marched on Genoa by way of Alessandria; or, lastly, he might have marched on Milan, and there have united his army with Moncey's corps. In his memoirs Napoleon himself has discussed the advantages and disadvantages of these plans as follows:—
"Of these three courses, the first was contrary to the true principles of war. Since Melas had considerable forces with him, the French army, therefore, would run the risk of fighting without having a certain retreat, Fort Bard not being then taken. Besides, if Melas should abandon Turin and move on Alessandria, the campaign would be a failure, and each army would find itself in its natural position: the French army resting upon Mont Blanc and Dauphiné; and that of Melas with its left at Genoa, and in its rear the fortified places of Mantua, Placentia, and Milan.
"The second course appeared impracticable: how hazardous would have been the situation of the French between the Po and Genoa, in the midst of an army so powerful as that of the Austrians, without any line of operations[9] (communication), any assured retreat.
"The third course, on the other hand, presented every advantage: the French army, once in possession of Milan, would secure all the magazines, depots, and hospitals, of the enemy's army; it would join the left under General Moncey, and have a safe retreat by the Simplon and St. Gothard. The Simplon led to the Valais and Sion, whither all the magazines of provisions for the army had been sent. The St. Gothard led into Switzerland, of which we had been in possession for two years, and which was covered by the Army of the Rhine then on the Iller. In this position the French general was at liberty to act as he pleased; if Melas should march with his whole army from Turin upon the Sesia and the Ticino, the French army could give him battle with this incalculable advantage, that, if it should be victorious, Melas, with his retreat cut off, would be pursued and driven into Savoy; and if it should be defeated, it could retreat by the Simplon and the St. Gothard. If Melas, as it was natural to suppose, should move towards Alessandria in order to join the army coming from Genoa, it might be hoped that, by advancing towards him and crossing the Po, he might be met and be forced to fight before he could reach Alessandria. (In other words, before the troops of Melas, and of General Ott, coming from Genoa, could unite at Alessandria.) The French army having its rear secured by the river, and by Milan, the Simplon, and the St. Gothard; while the Austrian army, having its retreat cut off, and having no communications with Mantua and Austria, would be liable to be thrown upon the mountains of the western coast of Genoa, or entirely destroyed, or taken at the foot of the Alps, at the Col di Tenda and in the county of Nice. Lastly, by adopting the third course, if it should suit the First Consul, when once master of Milan, to suffer Melas to pass, and to remain between the Po, the Adda, and the Ticino, he would thus, without a battle, reconquer Lombardy, and Piedmont, the Maritime Alps, and the Genoese territory, and raise the blockade of that city; these were flattering results to anticipate."
Bonaparte has been severely criticised for not taking the second course, which he has so briefly discussed in his memoirs. It has been represented that in marching on Milan, he sacrificed Masséna, when he might have marched directly to the relief of Genoa by way of Alessandria, and thus have saved his lieutenant the humiliation of a surrender. But what are the facts? They are that Melas sent orders to General Ott to raise the siege of Genoa before the Army of Reserve had even reached Milan. Had, therefore, Bonaparte crossed the Po at Chivasso, attacked and driven back Melas, and marched on Alessandria, he could not have brought relief to Masséna any earlier.
If Bonaparte had crossed the Po, he could undoubtedly have defeated Melas and driven him back to Alessandria; but here the Austrian commander, protected by the fortifications of the city, would doubtless have made a stand, and would have collected a large force to oppose Bonaparte. In this position, Melas would be joined by General Elsnitz, already marching on Alessandria, and could receive re-enforcements from General Ott and from General Vukassovich. Thus, in a short time, he could outnumber Bonaparte's army. Moreover, at Alessandria he could prevent the junction of Moncey's corps with the Army of Reserve, and might possibly be able to defeat them in detail.
In this position, Bonaparte, if defeated, would have no unobstructed line of retreat, for Fort Bard was still held by the Austrians; and, if victorious, he could do no more than force Melas back along the great highway to Mantua. In fact, should Melas be defeated at Alessandria, he could fall back to the fortress of Tortona or to the Stradella Pass, and there occupy another strong position. Here, with the re-enforcements that would doubtless join him from Genoa, from Vukassovich's corps, and from the fortresses in his rear, he would still have great chances of success.
In short, it would have been the height of folly for Bonaparte, with no secure line of retreat, to march into the centre of the Austrian theatre of operations, and expect to conquer Italy with but thirty-five thousand men. Even though it had been necessary to sacrifice Masséna, Bonaparte would have been justified in marching on Milan; for, in no other way could he be joined by Moncey's corps; in no other way could he sever the Austrian communications, and in no other way could he hope to defeat Melas and conquer Italy. Victory was his object.