On 13 July 1870, a report of an encounter at Bad Ems was published in an edited form by Otto von Bismarck. The edited text inflamed public opinion in France and Prussia and helped push the crisis toward open conflict. This set the stage for the Franco-Prussian War, during which German unification moved from diplomacy to wartime politics.
France declared war on Prussia on 19 July 1870. The war quickly drew in other German states aligned with Prussia, making it a conflict that could reshape the balance of power in Central Europe. The war’s course created both pressure and opportunity for a new German national state under Prussian leadership.
German forces began the Siege of Paris on 19 September 1870. The long siege weakened the French government’s position and kept the German high command and political leaders gathered near Versailles. That proximity mattered later: Versailles became the stage for the empire’s proclamation in January 1871.
In November 1870, treaties were concluded between the North German Confederation and the southern states of Baden, Hesse (south of the Main), Bavaria, and Württemberg. These agreements set conditions for those states to join a larger German federation while keeping certain special rights in some areas. The treaties were the key legal bridge from the North German Confederation to a broader German state.
On 1 January 1871, a provisional constitutional arrangement took effect as the southern states’ accession agreements came into force. This step effectively broadened the North German Confederation into a new, larger German federal structure pending final constitutional consolidation. It created continuity in institutions while preparing for the new imperial title and the final constitution in spring 1871.
On 18 January 1871, King Wilhelm I of Prussia was acclaimed German Emperor in the Hall of Mirrors at Versailles. The ceremony symbolized that the wartime coalition of German states was being turned into a single empire under Prussian leadership. It also underscored that unification was achieved through agreements among rulers and wartime victory, not through a single popular vote.
The Armistice of Versailles took effect on 28 January 1871, ending the active phase of the Franco-Prussian War. With major fighting paused, the political focus shifted to settlement terms and to formalizing the new empire’s legal structure. The armistice also made it possible to hold elections for an all-German parliament soon afterward.
On 3 March 1871, elections were held for the first Reichstag (imperial parliament). The vote provided a national legislature for the new political entity and helped legitimize the transition from wartime alliance to constitutional empire. This Reichstag would soon vote on the final constitutional text.
On 16 April 1871, the Constitution of the German Empire was enacted. It largely built on the 1867 constitution of the North German Confederation, creating a federal state with a Kaiser (emperor), a Bundesrat (council representing the states), and a Reichstag elected by broad male suffrage. The constitution defined how authority was shared—often unevenly—between the empire and its member states.
The imperial constitution came into force on 4 May 1871. This marked the shift from the provisional arrangements of early 1871 to a stable constitutional order for the German Empire. With the constitution in effect, the new institutions—especially the Kaiser, chancellor, Bundesrat, and Reichstag—had a clear legal basis for governing.
On 10 May 1871, France and the German Empire signed the Treaty of Frankfurt, formally ending the war. The treaty required France to cede Alsace and part of Lorraine and to pay a large indemnity, with German occupation tied to payment. The peace settlement both strengthened the new empire and planted long-term tensions in Franco-German relations.
By May 1871, Germany had moved from proclamation (18 January 1871) to an operative constitution (effective 4 May 1871) and an international peace settlement (10 May 1871). These steps turned wartime unification into a functioning state with defined institutions and legal rules. The result was a federal empire dominated by Prussia but supported by constitutional structures that would last until 1918.
Proclamation of the German Empire at Versailles and the 1871 Constitution (January–May 1871)