It is clear that there was one way in which the union might be brought about almost without resistance, and that was, if France were to make an unprovoked attack upon Germany, an attack so completely without reason and excuse that the strong national passion it provoked might in the enthusiasm of war sweep away all minor differences and party feelings.

There was another element which we must not omit.  These years witnessed the growth in determination and in power of the Ultramontane party.  We can find their influence in every country in Europe; their chief aim was the preservation of the temporal power of the Pope and the destruction of the newly created Kingdom of Italy.  They were also opposed to the unity of Germany under Prussia.  They were very active and powerful in South Germany, and at the elections in 1869 had gained a majority.  Their real object must be to win over the Emperor of the French to a complete agreement with themselves, to persuade him to forsake his earlier policy and to destroy what he had done so much to create.  They had a strong support in the person of the Empress, and they joined with the injured vanity of the French to press the Emperor towards war.

In 1867, war had almost broken out on the question of Luxemburg.  Napoleon had attempted to get at least this small extension of territory; relying on the support of Prussia he entered into negotiations with the King of Holland; the King agreed to surrender the Grand Duchy to France, making, however, a condition that Napoleon should secure the assent of Prussia to this arrangement.  At the very last moment, when the treaty was almost signed, Bismarck made it clear that the national feeling in Germany was so strong that if the transaction took place he would have to declare war against France.  At the same time, he published the secret treaties with the southern States.  These events destroyed the last hope of maintaining the old friendly relations with Napoleon; “I have been duped,” said the Emperor, who at once began reorganising and rearming his forces.  For some weeks there was great danger of war concerning the right of garrisoning Luxemburg; this had hitherto belonged to Prussia, but of course with the dissolution of the German Confederation the right had lapsed.  The German nation, which was much excited and thought little of the precise terms of treaties, wished to defend the right; Bismarck knew that in this matter the Prussian claim could not be supported; moreover, even if he had wished to go to war with France he was not ready; for some time must elapse before the army of the North German Confederation could be reorganised on the Prussian model.  He therefore preserved the peace and the matter was settled by a European Congress.  In the summer of 1867, he visited Paris with the King; externally the good relations between the two States were restored, but it was in reality only an armed peace.