The relations of the four Powers at this time were very remarkable.  All turned on Venetia.  The new Kingdom of Italy would not rest until it had secured this province.  Napoleon also was bound by honour to complete his promise and “free Italy to the Adriatic”; neither his throne nor that of his son would be secure if he failed to do so.  A war between Austria and Prussia would obviously afford the best opportunity, and his whole efforts were therefore directed to preventing a reconciliation between the two German Powers.  His great fear was that Austria should come to terms with Prussia, and surrender the Duchies on condition that Prussia should guarantee her Italian possessions.  When Bismarck visited Napoleon at Biarritz, the first question of the Emperor was, “Have you guaranteed Venetia to Austria?” It was the fear of this which caused his anger at the Treaty of Gastein.  On the other hand, Bismarck had his reasons for anxiety.  It was always possible that Austria, instead of coming to terms with Prussia, might choose the other side; she might surrender Venetia in order to obtain French and Italian support in a German war.  The situation indeed was this:  Austria was liable at any moment to be attacked by both Italy and Prussia; it would probably be beyond her strength to resist both assailants at the same time.  A wise statesman would probably have made terms with one or the other.  He would have either surrendered Venetia, which was really a source of weakness, to Italy, or agreed with Prussia over the Duchies and the German problem, thereby gaining Prussian support against Italy.  The honourable pride of Mensdorf and the military party in Austria refused to surrender anything till it was too late.

None the less, the constant fear lest Austria should make terms with one of her enemies for a long time prevented an alliance between Prussia and Italy.  The Italians did not trust Bismarck; they feared that if they made a treaty with him, he would allow them to get entangled in war, and then, as at Gastein, make up his quarrel with Austria.  Bismarck did not trust the Italians; he feared that they and Napoleon would even at the last moment take Venetia as a present, and, as very nearly happened, offer Austria one of the Prussian provinces instead.  It was impossible to have any reliance on Napoleon’s promises, for he was constantly being pulled two ways; his own policy and sympathies would lead him to an alliance with Prussia; the clerical party, which was yearly growing stronger and had the support of the Empress, wished him to side with the Catholic power.  In consequence, even after his return from France, Bismarck could not pass a day with full security that he might not find himself opposed by a coalition of Austria, France, and Italy; the Austrians felt that they were to be made the victims of a similar coalition between Prussia, France, and Italy; France always feared a national union between the two great German Powers.