After victory in the Austro-Prussian War of 1866 CE, Prussia had gained a lot of territory and formed the North German confederation, a proto-German state.
France was greatly upset by this new rival and demanded compensations, which were denied.
Both sides eyed each other warily and prepared to take up arms.
When France blocked the appointment of a Prussian prince as king of Spain, the Prussian leader Otto von Bismarck altered a telegram, goading France into declaring war.
The southern German states, at the time not yet unified, sided with Prussia.
The French army was about 400,000 strong, some regulars, including veterans of previous campaigns, and some conscripts.
When the war broke out many reservists were called up, though their mobilization and organization was chaotic.
The total army of Prussia and its allies numbered 1,200,000, all conscripts, who mobilized a lot faster.
The Germans had inferior rifles but superior artillery guns.
The Prussian general staff had prepared a plan for an offensive, deploying the troops in small mobile groups.
Meanwhile the French set out to fight a defensive war, intending to use their rifles and machine guns to keep the enemy at bay
and hoping, in vain, that Austria and the major southern German states would side with them.
The war started in Lorraine.
The French, under pressure from the public to score a success, moved first and overran the border town of Saarbrücken.
But actually they had moved too soon because their mobilization was still in progress.
The Germans, whose railway system was much more streamlined than the French, did so much faster.
They were ready to encircle the French once they invaded Germany.
Instead the latter quickly retreated to a long defensive line that stretched from Metz to Strasbourg.
This deployment lacked cohesion, allowing the Germans to defeat them one by one.
The Prussians, appraising the situation, attacked.
They won battles at Wissembourg, Spicheren and Wörth.
The inexperience of the Germans caused problems, but their numbers allowed them to overcome the isolated French forces.
The latter could have turned the tide at the next two battles, near Mars-La Tour and Gravelotte.
The first saw saw the last major cavalry engagement in Europe; the second was the largest of the war, which cost 28,000 lives, mostly German.
After the two battles the Germans were exhausted, yet the French did not counterattack because they were spent too.
Some of the French were besieged at Metz, while others retreated.
The Prussians pursued them hotly, surrounded and defeated them decisively at Sedan.
They captured an entire field army, including Napoléon III, the French emperor.
After one month, France was effectively defeated.
In an echo of the French Revolution, the Second French Empire was overthrown and the Third Republic proclaimed.
Von Bismarck, wary of possible entry into the war by other European powers, made peace proposals to the new government.
The French were willing to cede some colonial possessions, but not the eastern French territory that the Germans wanted.
So the war continued.
France started to recruit a militia army, spread all over the country.
The Prussians, without a concentrated army to do battle against, marched to Paris and started to besiege the city.
This turned public opinion in Europe, which had started out in their favor, against them.
The French raised several hundreds of thousands of troops, dispersed over their country.
Over five months they fought against the Germans, suffered several more defeats but also scored some victories by using guerrilla tactics.
The Germans were not prepared to fight all over France and occupied only the northeast.
Eventually the impending fall of Paris, which was starving, brought France to its knees.
An armistice was signed and several months later the Treaty of Frankfurt brought peace, though it was a humiliating one for France.
It ceded most of Alsace and parts of Lorraine, had to pay an indemnity and endure German occupation as long as it was not paid fully.
The Third Republic remained; Napoleon III died in exile in England.
The war unified Germany and created the German empire, the second after the Medieval Holy Roman Empire.
Prussia had won because of its large scale conscription, rapid mobilization, good communications, efficient general staff and competent officers who displayed initiative.
Also their aggressive use of artillery gave them an advantage over the French riflemen.
After the war, other countries started to organize their armies along similar lines.
War Matrix - Franco-Prussian War
Geopolitical Race 1830 CE - 1880 CE, Wars and campaigns