The Franco-Prussian War of 1870-1871 was a conflict between France, led by Emperor Napoleon III, and Prussia under Chancellor Otto von Bismarck. It resulted in the fall of Napoleon III’s regime and the unification of Germany under Prussian dominance.
Causes
The main cause of the war was the disruption of the balance of power established in Europe at the Congress of Vienna in 1815, exacerbated by Prussia’s resounding victory over Austria. After the decisive battle of Sadowa, Bismarck expanded Prussian control over much of northern Germany and sought to forge a stronger customs union with southern Germany, which was viewed as a direct challenge to French authority. In 1866, during armistice negotiations between Prussia and Austria, Napoleon III opposed any union between Prussia and the southern German states. He subsequently ordered military mobilisation that summer, threatening war if Bismarck attempted to annex Bavaria, Württemberg, or Baden.
By that time, France sought to assert itself as a leading power in Europe, but its position was challenged by Prussia’s rising influence. Moreover, it struggled with internal difficulties as Napoleon III faced pressures from republican leaders demanding democratic reforms and the constant threat of revolution. Despite these internal political challenges, by 1870 France had consolidated its military strength through army reforms. This, together with the rise of nationalism, an anti-Prussian government, the setbacks of the Second French intervention in Mexico, and diplomatic failures to secure consensus at home pushed France closer to war with Prussia.
However, the final trigger of the crisis was the candidacy of Prince Leopold for the throne of Spain, proposed by the then Prime Minister, General Juan Prim. This move greatly favoured Prussia, granting them a significant strategic advantage over France. Consequently, Napoleon III manoeuvred to prevent Leopold from ascending to the Spanish throne, successfully securing a public renunciation from Leopold’s father, Charles Anthony of Hohenzollern-Sigmaringen, on behalf of his son.
Despite this renunciation, the French government deemed verbal assurances from Charles insufficient and dispatched an ambassador to Bad Ems, where King Wilhelm I of Prussia was vacationing, to secure a written renunciation from Leopold. Meanwhile, Bismarck aimed to provoke French aggression to mobilise patriotism and justify Prussia’s role as the leading state in Germany. However, he preferred France to initiate hostilities first to avoid being seen as the aggressor.
To accomplish this, Bismarck drafted a telegram summarising the conversation between King Wilhelm and the French ambassador. Bismarck’s version of the telegram, known as the Ems Telegram, was edited to portray Wilhelm’s stance as more confrontational than it was. The edited telegram suggested that King Wilhelm had snubbed the French envoy, which outraged public opinion in both countries. Napoleon III and his government, feeling insulted by the telegram’s contents, used it as a pretext to declare war on Prussia on July 19, 1870.
The War
Initially, the French army planned to advance eastward as quickly as possible and initiate hostilities on German land. However, battle after battle, the French were forced to retreat further into their own country. Within a few weeks, the Prussian army was fighting deep within enemy territory. The Battle of Gravelotte marked a crucial turning point in the war, signifying a significant Prussian victory and sealing the fate of the French army, which comprised the best troops of the French military. After numerous defeats in the first weeks of the war, the French army retreated to Sedan in northern France to regroup. Still, the Prussian forces relentlessly pursued and eventually surrounded them. On September 1-2, 1870, the Battle of Sedan resulted in the capture of Emperor Napoleon III and his army, effectively deciding the war in favour of Prussia and its allies.
However, Napoleon III’s surrender did not end the war. Upon news reaching Paris, a popular uprising led to the proclamation of the Third Republic and a Government of National Defense was formed. Bismarck had anticipated a swift surrender, but with no legitimate authority to negotiate, he ordered his troops to besiege the French capital. By September 20, the siege of Paris was underway. Meanwhile, the new Government of National Defence initially considered surrender in exchange for some colonies and war reparations. However, upon hearing Bismarck’s harsh conditions demanding Alsace, Lorraine, and various frontier fortresses, they chose to continue the war at all costs.
Faced with continuous setbacks and the harshness of the siege of Paris, the Government of National Defense eventually decided to negotiate an armistice at Versailles. Bismarck agreed only to lift the siege in exchange for the surrender of several key fortresses crucial for Paris’ defence. President Trochu resigned, and two days later, on January 25, 1871, Favre signed the definitive armistice. In the meanwhile, Wilhelm I was proclaimed Kaiser at the Palace of Versailles, marking the completion of the German unification process led by the Kingdom of Prussia. This marked the end of the Franco-Prussian War, which resulted in the establishment of the Third French Republic and the loss of Alsace-Lorraine to the newly unified Germany.
Consequences
The Franco-Prussian War was strategically exploited by Prussia to establish the German Empire, unifying various small German states that historically lacked cohesion. Moreover, through the Treaty of Frankfurt, France was compelled to cede the resource-rich provinces of Alsace and Lorraine, in addition to paying substantial war reparations. This outcome heightened resentment in France, engendering deep-seated discontent that would endure for decades.
The birth of the German Empire not only challenged the dominance of France, Russia, and Austria-Hungary in Europe but also emerged as an economic rival to powers such as the vast British Empire. Tensions sparked by the loss of Alsace and Lorraine would play a crucial role decades later in the outbreak of the First World War, which ultimately led to the return of these provinces to France following Germany's defeat.
