Since the mountains and outlying works surrounding Genoa made it a veritable stronghold, Bonaparte calculated that the Army of Italy could maintain itself there against greatly outnumbering forces; and that the Austrians would hardly dare to force the Apennines and push forward in order to invade France while thirty thousand men remained undefeated in their rear. In this position, too, Masséna could, at any time, leave a small force to hold Genoa, then march rapidly westward along the south side of the Apennines, and arrive before any one of the threatened passes with almost his entire army; or should the Austrians force the Apennines and advance towards France, he could fall upon their flank and rear, and perhaps sever their communications, while his own communications with Genoa would be protected by the mountains on one side and by the sea on the other. In fact, this position would enable him to take advantage of the topography of the country to the fullest extent. If he should make an attack in force upon the Austrians from one of the passes in his possession, the mountains would protect him during his concentration, and would give strength to his position after his forces had united. If he should remain at Genoa, the fortifications and natural obstacles there would increase enormously his fighting power. It is evident, too, that he might march out of the city, force his way through the Apennines, and cut the communications of the Austrians in the valley of the Po. If, while holding the Apennines, he should advance with his main army over the Genoa-Nice road to attack the Austrians, he would be in a position where a victory would bring him great results, and where a defeat would do him but little harm. Should he be successful, he could sever the Austrian communications and perhaps ruin their army; should he be repulsed, he could fall back and seek safety in Genoa. "If," says Bonaparte in his instructions to Masséna, "Melas appear in the direction of Nice, you being at Genoa, let him come on, stir not from your position: he will not advance far if you remain in Liguria, ready to throw yourself upon his rear, or upon the troops left in Piedmont." In short, Bonaparte's design was so to make use of the works of nature and of art as to prolong the conflict and increase the effectiveness of Masséna's small army. Thus it was that Bonaparte expected thirty thousand French to defeat sixty thousand Austrians. Thus it was that he expected the Army of Italy to hold out against overwhelming odds till he himself could strike the decisive blow.