The immediate cause of the struggle was the proclamation of the infallibility of the Pope.  It might be thought that this change or development in the Constitution of the Roman Church was one which concerned chiefly Roman Catholics.  This is the view which Bismarck seems to have taken during the meetings of the Vatican Council.  The opposition to the decrees was strongest among the German Bishops, and Prince Hohenlohe, the Prime Minister of Bavaria, supported by his brother the Cardinal, was anxious to persuade the Governments of Europe to interfere, and, as they could have done, to prevent the Council from coming to any conclusion.  Bismarck refused on behalf of the Prussian Government to take any steps in this direction.  The conclusion of the Council and the proclamation of the decrees took place just at the time of the outbreak of war with France.  For some months Bismarck, occupied as he was with other matters, was unable to consider the changes which might be caused; it was moreover very important for him during the negotiations with Bavaria, which lasted all through the autumn, not to do anything which would arouse the fears of the Ultramontanes or intensify their reluctance to enter the Empire.

In the winter of 1870 the first sign of the dangers ahead was to be seen.  They arose from the occupation of Rome by the Italians.  The inevitable result of this was that the Roman Catholics of all countries in Europe were at once given a common cause of political endeavour; they were bound each of them in his own State to use his full influence to procure interference either by diplomacy or by arms, and to work for the rescue of the prisoner of the Vatican.  The German Catholics felt this as strongly as their co-religionists, and, while he was still at Versailles, a cardinal and bishop of the Church addressed a memorial to the King of Prussia on this matter.  This attempt to influence the foreign policy of the new Empire, and to use it for a purpose alien to the direct interest of Germany, was very repugnant to Bismarck and was quite sufficient to arouse feelings of hostility towards the Roman Catholics.  These were increased when he heard that the Roman Catholic leaders were combining to form a new political party; in the elections for the first Reichstag this movement was very successful and fifty members were returned whose sole bond of union was religion.  This he looked upon as “a mobilisation of the Church against the State”; the formation of a political party founded simply on unity of confession was, he said, an unheard-of innovation in political life.  His distrust increased when he found that their leader was Windthorst, a former Minister of the King of Hanover, and, as a patriotic Hanoverian, one of the chief opponents of a powerful and centralised Government.  The influence the Church had in the Polish provinces was a further cause of hostility, and seemed to justify him in condemning them as anti-German.  During the first session