Still the Archduke hoped to derive assistance from the natural or artificial defences of the strong country through which he was thus retreating, and in doing so was involuntarily introducing Buonaparte, after he should have surmounted the border frontier into the most fertile provinces of his brother's empire. The Lisonzo, usually a deep and furious torrent, closed in by a chain of impassable mountains, seemed to oppose an insurmountable barrier to his daring pursuers. But nature, as well as events, fought against the Austrians. The stream, reduced by frost, was fordable in several places. The river thus passed, the town of Gradisca, which had been covered with field-works to protect the line of the Lisonzo, was surprised and carried by storm, and its garrison of two thousand five hundred men made prisoners, by the divisions of Bernadotte and Serrurier. Pushed in every direction, the Austrians sustained every day additional and more severe losses. The strong fort of Chiusa-Veneta was occupied by Massena, who continued his active and indefatigable operations on the right of the retreating army. This success caused the envelopement, and dispersion or surrender, of a whole division of Austrians, five thousand of whom remained prisoners, while their baggage, cannon, colours, and all that constituted them an army, fell into the hands of the French. Four generals were made prisoners on this occasion; and many of the mountaineers of Carniola and Croatia, who had joined the Austrian army from their natural love of war, seeing that success appeared to have abandoned the imperial cause, became despondent, broke up their corps, and retired as stragglers to their villages. [Sidenote: TRIESTE AND FIUME.] Buonaparte availed himself of their loss of courage, and had recourse to proclamations, a species of arms which he valued himself as much upon using to advantage, as he did upon his military fame. He assured them that the French did not come into their country to innovate on their rights, religious customs, and manners. He exhorted them not to meddle in a war with which they had no concern, but encouraged them to afford assistance and furnish supplies to the French army, in payment of which he proposed to assign the public taxes which they had been in the habit of paying to the Emperor.[269] His proposal seems to have reconciled the Carinthians to the presence of the French, or, more properly speaking, they submitted to the military exactions which they had no means of resisting.[270] In the meanwhile, the French took possession of Trieste and Fiume, the only seaports belonging to Austria, where they seized much English merchandise, which was always a welcome prize, and of the quicksilver mines of Idria, where they found a valuable deposit of that mineral.