The unification of the railways caused greater difficulties. Nearly every state had its own system; there was the greatest variety in the methods of working and in the tariffs, and the through traffic, so important for the commercial prosperity of the country, was very ineffective. In Baden, Württemberg and Hanover the railways were almost entirely the property of the state, but in all other parts public and private lines existed side by side, an arrangement which seemed to combine the disadvantages of both systems. In 1871 three-quarters of the railway lines belonged to private companies, and the existence of these powerful private corporations, while they were defended by many of the Liberals, was, according to the national type of thought, something of an anomaly. Bismarck always attached great importance to the improvement of the railway service, and he saw that uniformity of working and of tariffs was very desirable. In the constitution of the empire he had introduced several clauses dealing with it. The independent administration of its lines by each state was left, but the empire received the power of legislating on railway matters; it could build lines necessary for military purposes even against the wish of the state in whose territory they lay, and the states bound themselves to administer their lines as part of a common system. In order to carry out these clauses a law was passed on the 27th of June 1873 creating an imperial railway office (_Reichseisenbahnamt_) for the purpose of exercising a general control over the railways. This office has done much in the matter of unifying the systems of various railways and of regulating their relations to the military, postal and telegraph organizations; it also took a leading part in the framing of the international laws regarding goods traffic; but the imperial code of railway law which it drafted has never been laid before the Reichstag. It effectively controls only the privately owned lines in Prussia. Yet, in setting it up, Bismarck had in mind the ultimate acquisition of all the railways by the empire. He found, however, that it was impossible to carry any Bill enforcing this. He therefore determined to begin by transferring to the imperial authority the Prussian state railways; had he been able to carry this out the influence of the imperial railways would have been so great that they would gradually have absorbed those of the other states. The Bill was carried through the Prussian parliament, but the opposition aroused in the other states was so great that he did not venture even to introduce in the Bundesrat a law empowering the empire to acquire the Prussian railways. In many of the state parliaments resolutions were carried protesting against the system of imperial railways, and from that time the preservation of the local railway management has been the chief object towards which, in Saxony, Bavaria and Württemberg, local feeling has been directed. The only