In fact, the most direct way is to establish a customs union, so that the goods of China and Prussia can circulate freely, just like the customs union established between Prussia and dozens of states in the North German region, which will greatly strengthen the trade advantages of Chinese goods in Central Europe, and Prussia's geography across the Baltic Sea and the North Sea is also very important, so that Chinese goods can be exported to Britain, northern France and Northern Europe more quickly.

But the establishment of such an alliance is very unrealistic, and neither Prussia nor China can actually accept it. According to the Prussian-North German Confederation, the customs union was dominated by Prussia, but not controlled by Prussia.

Rather, it is an independent body composed of personnel from each party, and this customs agency administers the customs duties of each member country, and the tax revenue is finally distributed to each member country according to the proportion. For such an alliance between China and Prussia, Prussia would fear that its sovereignty would be violated, and it would be impossible for China to accept the formation of a condominium with a small country like Prussia, because Hamburg could manage its own customs with Prussia, and China could not manage its own customs with the Prussians.

Therefore, it is impossible to establish a customs union, so the only way to connect the two countries more quickly is to connect the two countries more quickly through railways, which are basically built at present. During Prussia's control of Poland, a railway between Prussia and Poland was built, mainly for military reasons. The difficulty of building railways on the Bode Plains was so small that they were built quickly and at a low cost, and soon became a dense network.

China's railways, through Poland into Prussia, do not have any difficulties in transportation, and because of the relationship with the Chinese railways, the railways in Poland even use Chinese standards, using two-meter-wide standard tracks, while many Prussian railways use British standards.

Bismarck could allow some railway standards to be changed, so that the two railway lines from Warsaw to East Prussia and Hamburg would be changed to Chinese standards, so that the railways would not have to change trains, and all the way to the Baltic and North Seas would be possible.

But this was not enough to strengthen China's ties with Prussia. A closer customs union cannot be established, and mere modification of railway lines is too weak. Bismarck decided to establish a free-passage agreement with China, and the cross-border train transportation process was hampered by different track standards and by legal and jurisdictional issues between different countries.

Every time you pass through an administrative district, you have to stop for inspection, and even unload the truck for inspection, repack, and then load it. This greatly affects the efficiency of transportation and increases the cost of transportation.

However, after the establishment of the German Customs Union, this problem was solved, and even the biggest motive for the establishment of the Customs Union was to unify the problem of trade and transportation, and the income from tariffs was only secondary, especially for a large country like Prussia, the tariff revenue was not the largest income, and the increase in domestic production was the greatest source of wealth.

It is not possible to establish a customs union with China, but it is possible to establish a transportation alliance, which can give China the right to freely transit Prussia by rail, of course, if it can get equal rights, it will be great good news for Prussia and even the entire German Customs Union, which will greatly improve North Germany's advantages in trade with China.

Whoever can sell something to China will get rich, this is already a consensus. So Bismarck thought that it would not be difficult for him to convince the Prussian king and the German Customs Union. However, China may not agree, because China is ten times the size of the whole of Germany, and it is understandable that they are not willing to accept the free passage of German trains in China on a reciprocal basis, and if Bismarck is willing to make unilateral concessions in this case, it will be difficult to convince the Prussian king and parliament to accept this, because it also involves a question of national dignity, and it is even more difficult to convince the North German Customs Union.

Bismarck, however, thought it was worth the effort, and that a free-passage agreement with China would be enough to bring China closer to Prussia and thus support Prussia on the Russian issue.

Next is the United Kingdom, and at this time a new problem arises, once it enters with China, it means estrangement from the United Kingdom. It will be more difficult to win Britain over Prussia on the Russian issue, especially when Britain has begun to see ensuring a certain degree of Russian strength as the greatest diplomatic counterweight to China.

Therefore, Bismarck decided to adopt an attitude of restraint towards Russia without challenging this attitude of Britain, so as to gain the support of Britain. If Prussia and Austria defeated Russia together, Prussia was willing to exercise maximum restraint and not divide up Russian territory too much, which was believed to be enough to bring Britain to Prussia. In order for Britain to remain silent from the outset, Prussia would need to make it clear to Britain from the outset, telling the British that Prussia had no interest in Russian territory, but only sought to recover the interests that should have belonged to Prussia.

After the completion of the plan, Bismarck formally communicated with the Chinese diplomatic department, first put forward an idea, which the other side was very interested in, and then the two sides negotiated in more detail on the basis of such an idea.

Sure enough, as Bismarck had guessed, the Chinese diplomatic service could not accept the passage of German trains through China's railway network, and they feared that the Germans would use this power to smuggle. It's just an excuse to feel unbalanced. The railways built by China in recent years are too huge, in just 20 years, 150,000 kilometers of railways have been built, every province has railways, and Germany's railways are only a few thousand kilometers.

Since he had guessed this a long time ago, Bismarck, of course, had already thought of a solution, and he prepared three sets of plans.

As a result, the second set of plans was recognized by the Chinese.

Germany did not require China to open all railway lines, but only to one railway line from Germany to China, and Bismarck asked for the same line that he had arrived from Germany by train, from Berlin to Jiangningfu. But China demanded that it not just Prussian railways, and he wanted Chinese trains to be able to travel through the entire railway network of the German Customs Union.

Bismarck also agreed. He has prepared the intention of unilaterally opening up the right of passage to China if China does not accept it, but the Chinese are sometimes very good at talking, probably because of the different worldviews in the cultural background, so that their understanding of interests is different from that of Westerners. In diplomatic negotiations, the Chinese are not as stubborn as the British in reciprocal relations, they often put themselves in the position handed over, but they are also not like the British, who calculate every account clearly, and hate to write every penny into the treaty. Therefore, sometimes the negotiation with the Chinese obviously feels uncomfortable, but the Chinese just insist, and sometimes they obviously find that they have taken advantage of something, and the Chinese do not care.

According to the Chinese, this is called leaving a line in everything and not doing things absolutely.

Therefore, it is understandable that the current situation has arisen, according to specific interests, China has opened a railway line of more than 10,000 kilometers, while the German Customs Union region has opened less than 10,000 kilometers, but in terms of power, China has exchanged the power of its own railway for the opening of railways in more than 30 countries in the German region, and both countries have acceptable reasons.

After the division of power is clear, there is the legal issue, how to ensure that Chinese trains are on German railways, and German trains are more convenient to pass on Chinese railways, reducing stop inspections and frequent customs clearance processes.

Bismarck proposed the creation of a condominium, a unified body similar to the Customs Union, to manage customs clearance on the railway. Chinese trains, after entering the German region, as long as they do not stop along the way to unload the goods, do not need to be inspected, as for the unloaded goods, the customs department for customs clearance, taxation and other normal management, the same is true for German trains on Chinese railways.

In terms of the setting of this management body, it is best for Bismarck to be close to the people, not with too strong political overtones, and China has also won the war, not because it is not to give in to Germany, but that China has always left a large number of traditions of non-governmental autonomy in the management of commerce. In the dynastic era, officials did not compete with the people for profit, and at the same time, the management of the collection of commercial taxes and other management needed to rely on the knowledge and experience of private merchants, because civil officials from the imperial examination generally did not have commercial talents.

In the Great Zhou Dynasty, Zhou Lang still inherited these commercial cultural traditions, and in the management of commerce, the administrative department was allowed to cooperate with merchant groups such as chambers of commerce, as a management method and a political balance, so that the government was less involved in the operation of commerce, so as not to suppress commerce by the strong administrative forces in the past.

Since the Chinese side of the railway happens to be managed by a railway company, the national railway company, China directly authorized this company to send people to manage and be responsible for communicating with China's customs department. On the German side, they sent their own representatives to administer it, and the two sides formed a joint Sino-German railway transport management committee, which was a non-governmental organization in nature, but both sides gave the committee some necessary administrative powers to give them legal administrative functions.

As soon as the basic terms were reached, Bismarck rushed back to Germany, and now that his mission in China was over, he needed to persuade Prussia and the rest of the German states to accept the agreement, while explaining possible British intervention.