While these various events were transpiring at sea, from the evacuation of Corsica to the battle of St. Vincent, Bonaparte in Italy was still holding the line of the Adige and blockading Mantua. His posture therefore was essentially one of defence. The vigor and sagacity with which he resorted to offensive movements the instant the enemy drew down from the Tyrol to attack him, and the brilliant character of the victories won by him, obscure to most the fact that he was really on the defensive; holding on, amid risks and discouragements, to the conquests already made, and unable to attempt more until Mantua fell. The glories of Castiglione, Arcola, Rivoli, conceal this crucial feature of his situation, and the consequently important bearing of the presence of the British fleet, encouraging the dispositions of Naples and the Pope, which were distinctly hostile to the French. Nothing less than Bonaparte's energy and genius could have grappled successfully with such a situation; and his correspondence betrays his fear that, by the co-operation of the fleet, these dangers in the rear might become too great even for him. When Mantua capitulated on the 2d of February, Bonaparte turned first upon the Pope, whom he accused of violating the armistice concluded the previous June. His Holiness at once submitted, and on the 19th of February signed a peace, abandoning his right to his northern provinces,—Bologna, Ferrara and the Romagna,—and ceding to France, until the end of the war, Ancona, a good seaport on the Adriatic.
On the 10th of March, having completed all the dispositions that seemed necessary to secure his rear, Bonaparte advanced against the Austrians. The young Archduke Charles, whom the campaign of 1796 on the Danube had revealed to Europe as gifted with military talents of a very high order, had been sent to oppose him; but it was too late to resist on the plains of Italy, or even on the Italian side of the mountains. The French crossed the Tagliamento on March 16, and pushed up through the gorges of that stream and of the Isonzo into the eastern Alps. On the 23d Trieste was occupied. The Archduke retired continuously, barely disputing difficult positions with the enemy. His mind was fixed not to fight until he had drawn the French far into Germany, and had collected his own resources,—a decision whose wisdom Bonaparte sealed with his own commendation. "If the enemy had committed the folly of awaiting me," he wrote to the Directory, "I should have beaten them; but if they had continued to fall back, had joined a part of their forces from the Rhine, and had overwhelmed me, then retreat would have been difficult, and the loss of the Army of Italy might entail that of the republic. We must not shut our eyes to the fact that, though our military position was brilliant, we have not simply dictated the conditions."[151] Italy, too, was fermenting behind him. The moral effect, however, of this unopposed advance through the mountains of Carinthia brought the House of Austria to terms; and on the 18th of April preliminaries of peace were signed at Leoben, only sixty miles from Vienna. Though the formal treaty was not concluded until six months later, this transaction marked, for that time, the end of hostilities between Austria and France, which had then lasted five years,—from April, 1792, to April, 1797.