It commenced on 18 August with adoption of the North German Confederation Treaty establishing the North German Confederation , initially a military alliance de facto dominated by Prussia which was subsequently deepened through adoption of the North German Constitution. The process symbolically concluded when most of the south German states joined the North German Confederation with the ceremonial proclamation of the German Empire i. Despite the legal, administrative, and political disruption caused by the dissolution of the Holy Roman Empire in , the German-speaking people of the old Empire had a common linguistic, cultural, and legal tradition.
European liberalism offered an intellectual basis for unification by challenging dynastic and absolutist models of social and political organization; its German manifestation emphasized the importance of tradition, education, and linguistic unity. Economically, the creation of the Prussian Zollverein customs union in , and its subsequent expansion to include other states of the Austria under Austrian Empire -led German Confederation , reduced competition between and within states.
Emerging modes of transportation facilitated business and recreational travel, leading to contact and sometimes conflict between and among German-speakers from throughout Central Europe. The model of diplomatic spheres of influence resulting from the Congress of Vienna in β after the Napoleonic Wars endorsed Austrian dominance in Central Europe through Habsburg leadership of the German Confederation, designed to replace the Holy Roman Empire.
The negotiators at Vienna took no account of Prussia's growing strength within and declined to create a second coalition of the German states under Prussia's influence, and so failed to foresee that Prussia Kingdom of Prussia would rise to challenge Austria for leadership of the German peoples.
Historians debate whether Otto von Bismarck β Minister President of Prussia βhad a master plan to expand the North German Confederation of to include the remaining independent German states into a single entity or simply to expand the power of the Kingdom of Prussia. They conclude that factors in addition to the strength of Bismarck's Realpolitik led a collection of early modern polities to reorganize their political, economic, military, and diplomatic relationships in the 19th century.
