Bismarck had to fight three wars to unify Germany. The 1864 Danish War helped Bismarck consolidate his internal position in Prussia. The War of 1866 ousted Austria from leadership in Germany for good. The Franco-Prussian War of 1870-71 brought the South under the aegis of the Prussian eagle. That was the unification process in a nutshell. Now let us look at it in some detail.
I. War with Denmark
Liberal sentiment in Germany had always been stirred by a desire to separate Schleswig-Holstein from Denmark. The liberals called for a repudiation of international agreements by Prussia (such as the 1852 Protocol which put the Danish issue on ice), while Bismarck declared in the Diet that he would not be a party to a breach of international obligations.
So Bismarck made an agreement with Austria, the avowed enemy of German unity, to proceed within the context of the 1852 Protocol. The two powers then sent an ultimatum to Denmark on January 16, 1864 demanding a withdrawal of the constitution of November18 (which incorporated Schleswig in Denmark) within 48 hours or face military action. Denmark, counting on the support of the European Powers, rejected the ultimatum. France hesitated to join England, which refused to act alone. So the powers did nothing. An attempt at mediation also failed. Denmark was therefore reduced to submission by Prussian and Austrian military force.
In the Treaty of Gastein (August 1865) Prussia and Austria decided how to dispose of the acquired duchies. The two powers decided to rule the two duchies jointly, with Austria administering Holstein and Prussia administering Schleswig. Prussia was given certain military roads through Holstein and command of Kiel, which was to be a port of the German Confederation. Both duchies were compelled to join the Zollverein, which was of course to Prussia's benefit since she controlled the customs union for all practical purposes.
But that was not all. Prussia also annexed Lauenburg, although she paid a price of 2.5 million thaler for it. The German claimant to the throne of the two duchies, Augustenberg, was completely ignored. All this seemed fair enough, although Prussia obviously got the better end of the stick. But Bismarck had no intention of leaving things as they were. It is surprising that the statesmen of Austria did not see this.
II. War with Austria
Bismarck believed that trouble and eventual war with Austria would be inevitable. His entire policy from 1863 to 1866 was predicated on war with Austria. He had made sure that Russia would not intervene when he sympathized with Russia in crushing the Polish revolution of 1863. Napoleon III was maneuvered into a favorable position by all kinds of vague promises for territorial aggrandizement in 1865. An alliance with Italy was made in April 1866, through Napoleon's assistance, which stipulated that Italy would come to the aid of Prussia if a war with Austria broke out in three months. Bismarck also tried to get Bavarian support but failed.
A. A bit of Caesarism
It is interesting that not a single German state was with Prussia when the war actually came. The liberal and progressive majority in the Prussian diet was somewhat mollified after the Danish war, but still actively opposed to the government. Bismarck then adopted some Caesarism from Napoleon III and Disreali. He presented a plan to the Confederate Diet in April 1866, which called for the acceptance of the 1849 electoral laws, including universal equal and secret ballot.
It was a tactical move to embarrass Austria since he knew Austria would oppose the planned reform. He really believed that universal suffrage would work to his advantage, hoping that the clergy and the landowners would be able to win the peasants to the conservative side. The growth of the worker movement would also help, since Lasalle was the chief enemy of the liberals, whose main support came from the upper...