Unification of Germany: Origins, Wars & Bismarck’s Role

Unification of Germany: Origins, Wars & Bismarck’s Role
Proclamation of the King of Prussia as the king of the newly-created Germany, at the Palace of Versailles, on French territory. Painting by Anton von Werner. Public domain.

Until the second half of the 19th century, Germany, as a single sovereign state, did not exist. Instead, there was an abundance of small kingdoms, each with its prince: Bavaria, Hesse, Württemberg, Hanover, and Luxembourg are some examples. There were also two main kingdoms, distinguished by their larger territory and influence over the others: Austria and Prussia. The history of German unification corresponds to the gradual amalgamation of the territories of these kingdoms, in a process that, although it was dominated by the two German powers, it was decided by all the states of the region. In a way, all had some role in the unification wars and in the military victories or failures that defined these conflicts.

Origins of the Unification

The formation of modern Germany had its ideological kickoff with the Napoleonic Era and the cooptation of various European states by the French. For Napoleon, in general terms, only two German resources mattered: men to bolster the French army and money to finance it. Because of this, there emerged a predatory relationship, because France allied with local German elites and obtained everything it needed, at the expense of the German peoples. This cooptation mechanism, although successful in the short term, would contribute to forming some common traits among the various German peoples: aversion to France, nationalism, and militarism in defense of the homeland.

Undoubtedly, German identity was not uniform. Each population, depending on the circumstances of its exploitation by the French, reacted differently to this — which is why it is possible to talk about nationalisms and militarisms, in the plural. However, the general repudiation of the French, and not just the Napoleonic regime, was something uniform and special. This repudiation served as a bridge to connect the different identities of the region: the German peoples might have differed in their immediate purposes and objectives, but most of them (if not all) identified themselves in opposition to France.

At the end of the Napoleonic Era, the status quo in Central Europe had become unsustainable. There were a multitude of small states, generally weak and incohesive, which post-war architects saw as vulnerable to future French attacks. For the diplomatic representatives sent to the Congress of Vienna, it was essential to ensure an arrangement that consolidated the influence of the European powers and stabilized the Old Continent. Therefore, they decided to extinguish some kingdoms, favor others, and create a German Confederation: a single entity to politically unite the peoples who had until then lived with little integration. This confederation would be dominated by Austria and Prussia. Its role was to ensure that Central Europe would be more homogeneous and less vulnerable to French covetousness.

In political terms, there was greater German integration, through the Diet of Frankfurt (an arrangement among local monarchs), although Austria prevailed in it. Economic integration also increased, thanks to the advancement of the Zollverein, a customs union led by Prussian industry. Despite this, the region’s military strengthening — the cornerstone of the Vienna arrangement — did not happen right away. At that time, Prussia under Frederick William IV was modernizing its Armed Forces, developing them in a technical and scientific manner. However, Austria’s major security concerns were in the Italian Peninsula, where they had various strategic interests; and the other German states were too weak to proactively defend their own territories.

In the midst of the liberal revolutions of 1848, Prussia saw the creation of the so-called “Frankfurt Parliament”: an attempt to impose a constitution on the Prussian monarchy and unify the country with the other German kingdoms. The rebels were harshly suppressed by Frederick William IV, but their ideas would be reused later. Soon after, in 1849, based on the Frankfurt ideals, the monarch of Prussia proposed the unification of the German Confederation into a constitutional federation, led by him. Austria, which would be marginalized by this, turned against the proposal and convinced the other states of the danger of Prussian hegemony in Central Europe. Through the Punctation of Olmütz, an ad hoc agreement, Austrians and Prussians agreed to jointly resolve the future of the German Confederation. Without this, they might have opted for war.

Second Schleswig War (1864)

In the years following the Olmütz pact, facing a succession crisis in Denmark, the two German powers even attempted broader cooperation. The Duchies of Schleswig and Holstein had historical ties with the Germans but were personally linked to the Danish crown. However, with the death of the Danish monarch in 1863, his legitimate successor tried to institutionally bind both duchies to Denmark. This led Austrians and Prussians to consider the claim of another successor to the throne, who would be more favorable to German interests. However, the final response of the German Confederation was military and political: a deployment of troops to the duchies and an agreement between Austria and Prussia to define the region’s status.

The conflict that ensued upon the arrival of foreign forces in the Danish duchies is known as the “Second Schleswig War”. The literature often considers it the first war of German unification, as it resulted in the annexation of both Schleswig and Holstein to the German Confederation. According to the Gastein Convention (1865), Austrians and Prussians would share sovereignty over the duchies, but each of them would be administered separately.

This dynamic oil painting depicts a scene from the Second Schleswig War. It portrays an intense battle scene with soldiers engaged in combat. The soldiers, wearing various uniforms indicating different regiments, are shown advancing through a sandy embankment towards an enemy position. The foreground is filled with infantry soldiers armed with rifles and bayonets, some in the heat of battle, others fallen. The smoke from gunfire partially obscures the background, where flags are being raised amid the fight. The dramatic sky above suggests the chaos of the battle. Details such as facial expressions, the movement of soldiers, and scattered war equipment on the ground contribute to the vivid representation of 19th-century warfare in this painting.
In the Second Schleswig War, Austrians and Prussians fought against Denmark to control Schleswig and Holstein. Painting by Wilhelm Camphausens. Public domain.

Austro-Prussian War (1866)

The cooperative spirit of the Gastein Convention concealed the continued tensions between the two German powers — after all, Austria increasingly felt threatened by a Prussia that was improving its Armed Forces and had major economic ambitions for the Zollverein. Similarly, the Prussian monarchy knew that its aspirations would challenge the Austrians.

Therefore, it is not surprising that, after the Second Schleswig War, members of the German Confederation did not settle into peace. Each German power sought international support to counter the actions of the other: Prussia aligned with the newly-formed Italy; Austria reinforced its ties with the Southern German states. The catalyst for the clash between them came in 1866 when the Austrians denounced the actions of their rivals in the German Confederation, and Prussia dissolved this association. As soon as Austria presented itself as the protector of the small German states against the supposed “Prussian aggression,” Otto von Bismarck, the Chancellor of Prussia, declared casus belli. Thus began the “Brothers’ War” (1866), the second German unification war, in Central Europe and Italy.

In the Italian Peninsula, Austria managed to fight relatively well, based on deadly confrontations that demoralized the Italians — mainly because this had been the main theater of operations for the Austrian forces for a very long time.

In the German theater of war, however, the situation was quite different. Prussia enjoyed all the technical, scientific, and military progress it had built in the previous decades. Its actions were organized, systematic, and extremely effective, partly due to a series of new weapons it possessed. On the other hand, Austrian deficiencies were evident: chaotic and demotivated troops were led by indecisive officers, who made wrong decisions and carried out problematic retreats.

In the Battle of Königgrätz, when the Austrians finally had a real chance to respond to their misfortune, it was already too late. Prussia won the war and imposed the creation of a North German Confederation (including the Northern German states and both Danish duchies) and the power to define (by force, if necessary) its relations with the Southern German states.

Franco-Prussian War (1870-1871)

While Prussia dealt with the consequences of the 1866 war, which catapulted its power in European territory, the Austrians suffered even more. Due to the Compromise of 1867, the Austrian Empire became a dual monarchy, composed of Austria and Hungary.

Although some integration between the Armed Forces of these monarchies was expected to happen, in practical terms, the Hungarians were not willing to support any military initiatives in German territory. Because of this, the most Austria could do to counter Prussian power was an “in principle” alliance with France, which feared Prussian hegemony in Central Europe. The French statesman Napoleon III also established another “in principle” alliance with the Italian monarch Victor Emmanuel, in exchange for the withdrawal of French troops occupying Rome in defense of the Catholic Church.

Napoleon III wanted to rally Austria and Italy as allies because Prussia challenged several French interests. To accept recognizing the emergence of the North German Confederation, he proposed the French annexation of Luxembourg (an area occupied by the French) and Belgium — what was promptly rejected by Prussia. Instead, Bismarck called an international conference, where the powers of the Concert of Europe agreed to make Luxembourg a neutral territory, which meant a defeat for France.

Another problem arose with a succession crisis in Spain. A relative of the King of Prussia intended to ascend to the Spanish throne, but this could corner France between two domains of the Hohenzollern dynasty — Spain on one side and Prussia on the other. These issues propelled Napoleon III to make a declaration of war, but this was postponed several times, as France was at a disadvantage against a militarily sophisticated and modern Prussia.

The first attempt to resolve the Spanish succession crisis was peaceful: a French ambassador traveled to negotiate with the King of Prussia. Although the monarch committed not to support his relative’s claims to the Spanish throne at that time, his refusal to make this commitment permanent became a bone of contention. In the Ems Dispatch, the Prussian Foreign Minister reported to Bismarck how the meeting between the ambassador and the Prussian king occurred. However, Bismarck deliberately altered this report, making the words in it offensive to both the Germans and the French. By releasing the edited text to the press, Bismarck fueled vigorous protests in Berlin and Paris. Thus, the third war of German unification began: the Franco-Prussian War (1870-1871).

For Napoleon III, the agreements with Austria and Italy ensured these alliances, although they were merely intentions. This miscalculation contrasted with Prussia’s ability to combine its own troops with those of the other German states — except Austria —, which had militarily progressed under Prussian influence. Thus, the conflict once again opposed well-prepared military forces against unprepared ones: although France managed to repel certain Prussian advances, its technical ineptitude prevented it from launching successful attacks. Moreover, even though the French had a wide range of troops, their numerical superiority did not compensate for the precision of German armaments. In the same year of 1870, therefore, the Second French Empire collapsed due to military failures, giving way to a republic, while Napoleon III became a prisoner of war.

Under the French Third Republic, however, the conflict persisted, and the coalition led by the Prussians reached the outskirts of Paris. At this point, the balance of forces had changed considerably: if the French were on the back foot, having an enemy surrounding their capital, the Germans also faced challenges. Being inside France, the German troops had to fight against both the Parisian resistance, symbolized by the Paris Commune, and the resistance of the French rural populations. This two-front war caused certain difficulties, which led Prussia to bombard Paris, as a means to force a local surrender. This did not work initially, but, over time, negotiations for peace began — and they were conducted under an evident imbalance between the two belligerents.

This historical black and white photograph depicts the aftermath of the bombing of Paris during the Franco-Prussian War. The scene shows a street with damaged buildings; some are partially collapsed, with visible rubble and destruction. The facades of the remaining structures are riddled with holes and show signs of bombardment. In the foreground, there's a horse-drawn carriage and some people going about their daily activities, indicating life continues amidst the ruins. A pile of debris is stacked by the side of the street, and in the background, an intact church bell tower rises above the devastation, contrasting with the surrounding destruction. The image captures a moment of resilience in a war-torn city.
Photograph of the Saint-Cloud region, on the outskirts of Paris, after the bombings carried out by the Germans. Image by Adolphe Braun. Public domain.

At the end of the negotiations between the French and the Germans, a ceasefire and a peace treaty were established, the Treaty of Frankfurt (1871), with the following highlights:

  • The unification of Germany would be officialized, with the coronation of King William I, previously of Prussia, as the monarch of the new country.
  • The Germans would annex the Alsace-Lorraine region.
  • France was to pay war indemnities to the Germans, and would be militarily occupied until this debt was paid off.
  • As a measure to reaffirm a defeat that, until then, was not accepted by the French people, a humiliating “victory parade” would take place in Paris.

This set of stipulations from the Treaty of Frankfurt would fuel, in the short and long term, Franco-German revanchism. While the French nation struggled to pay off its war debts and end the occupation of its territory, the Germans completed their process of integration and expanded their diplomatic activity, under the leadership of Bismarck. Yet the fallout of the war would remain latent in both states and, over the 20th century, would lead to new conflicts between them.


The unification of Germany was late, as it occurred only in the second half of the 19th century. However, it was a process that took place with great speed, as it united dozens of small monarchies in a period of just seven years.

After the founding of the country, Bismarck consolidated his power even more and orchestrated an alliance between nobles (Junkers) and bourgeoisie to industrialize the country. Domestically, German society was militarized, and the Army held immense political prestige. In international relations, unified Germany tried to propagate the idea that the country was satisfied with the status quo in Europe — in other words, that the Germans would avoid engaging in other wars. This was a deliberate strategy, aimed at the international isolation of France.

Bismarck remained in power until 1890, balancing his country amid the European powers. However, after the death of King William I, the chancellor was forced to resign by the new monarch, William II, who wanted to impose a foreign policy based on territorial and military expansionism. Such was Bismarck’s influence on German political life that, after his withdrawal, the Germans had less success in securing their objectives on the international stage. The shift of Germany from moderation to militarism can be understood as one of the long-term causes of World War I.




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