The Unification of Germany had a significant impact on the whole country, the empire, and the decades after that. It was the inauguration for Germany into the 20th century, and the dreaded World War I and World War II that were partially consequences of that unification.
On January 18th, 1871, in the Palace of Versailles in France, Germany was lawfully merged into the German Empire, a Prussia-dominated country state with federal components. Throughout the Franco-Prussian War, princes of German countries assembled there to declare King Wilhelm I of Prussia Emperor of the German Empire.
The Treaty of Verdun in 843 developed a confederated kingdom of German princedoms that had existed for over 1,000 years. Even so, till 1800, there was no development of a German country identity, owing to the independent nature of baronial states; most occupants of the Holy Roman Empire, beyond those straight governed by the emperor, determined themselves mainly with their prince, instead of with the Empire as a whole. Kleinstaaterei, or "small-statery," happened called a result of this practice. Improvements in transport and interactions brought these areas closer together by the nineteenth century.
Today, you can learn more about what made this unification so special, and how it led to other events in history.