It is this war, the one of 1870, where the lead-in to the general European war is first seen. While the Prussians did defeat the Austrians in the Austro-Prussian War, this was less impressive than it seems. Austria had never been taken seriously as a military power since the 18th Century. Prussia, by contrast, was taken seriously....as a middling power. In 1870 the Second Bonapartist Empire was seemingly at the height of its power. It should be noted that the French Empire in this war was the more technologically advanced of the two societies. It had machine guns (the mitralleuse
), it had the more esteemed record of the 19th Century (there's a reason people in the US Civil War despised German units, the idea then was that Germans were good poets and composers, shitty fighters). Too, there was the one French Empire, but multiple German states.
Yet Otto von Bismarck outmaneuvered the French. The war was in one sense the last succession war in European history. The cause of the war was a conflict over who was and who wasn't to succeed to the throne of Spain. The French preferred one candidate, and were extremely offended at the idea a Hohenzollern (the royal house of Prussia and later Imperial Germany) could possibly control France, and it also sparked fears of encirclement, and this was played up by Otto von Bismarck in his Ems Telegram. Thus on 19 July began the fateful war. Ironically given the jingoism in the US that's shown up since the Bush Administration as regards France the expectation was a lopsided Persian defeat. The French made the first move, occupying Saarbrucken.
Then the Prussian-led alliance of German states struck, and at Wissembourg, achieving a 60,000/8,000 lopsided superiority which led the French garrison there, naturally, to fall back. In the second battle, at Spicheren, 27,000 Prussians forced 24,000 French to retreat toward Metz. This battle was not planned, but a result of an overzealous attack by the Prussian general, Steinmetz, against the French general, Frossard. Ironically the very Prussian inferiority in guns meant that they took very high casualties in this battle despite winning it.
It was the Battle of Worth, where a German alliance army of 75,000 defeated a French army of 32,000, with the Prussian superiority in both quantity of artillery (300 guns to 101) and quality of artillery led them to a decisive victory over the French army. This battle is known as the cradle of Germany because it was the first instance of the Imperial-era "German" military where troops from the individual German states fought as one army. The French were soundly thrashed and forced to retreat yet again.
At the Battle of Mars-La-Tour an intended French move to Verdun was thwarted by von Bredow's death ride, the last instance of a successful cavalry charge in Europe. The French army, despite outnumbering the Prussia 127,000 to 30,000 was soundly whupped and forced to into the Siege of Metz, a major tactical and strategic victory (and one instance where this war resembled the Civil War). Similarly at Gravelotte a Prussian army under Helmuth von Moltke forced them altogether into Metz, this despite being as usual the side with the greater casualties.
From August into October of 1870 Metz was besieged by Prince Friedrich Karl of Prussia, who captured 186,000 troops under General Bazaine.
It would be at Sedan that a French army under the direct command of Louis-Napoleon Bonaparte numbering 120,000 was attacked by a Prussian army of 200,000 with as usual a decisive superiority of artillery. Louis-Napoleon had lost an earlier battle against the Prussians, but here the German-led alliance soundly defeated the French due both to superiority of numbers and especially in quantity and quality of artillery. The victory was decisive, marked the end of France's second experiment with Bonapartist rule, while Paris was besieged from September 1870 to January of 1871. Despite valiant and heroic efforts to break the siege, which also included deliberate firing on civilians by the Prussian-led alliance, Paris surrendered.
In January of this year, this happened:
German particularism was effectively dead. The German Empire was proclaimed in the Hall of Mirrors in the former palace of the Sun King, at Versailles (the very same place where the infamously botched treaty that dictated Germany's peace terms at the end of WWI was signed). With his son, the future (very short-lived) Kaiser Friedrich III behind him, and the noble von Bismarck in white in front of him, the King of Prussia who'd taken over from a deranged older brother had become German Emperor.
The war finally ended in 1871, with the fledgling German state taking Alsace-Lorraine from the French Third Republic and forcing on it a punitive indemnity. If this sounds familiar, Versailles was this dialed up to 11. Somehow the French overlooked that it hadn't worked very well with them, and was even less likely to do this with the Weimar Republic. The German Empire now existed, and one of Europe's potentially largest and richest states had been born. But from the harsh peace of 1871 came the future seed of which the French desire for an alliance with Russia was sown. Yet early on the German Empire signed the Drekaiserbund with the Russian Empire.
For a time the Russia of Alexander II, Tsar-Liberator, the Austro-Hungarian dual monarchy of Franz Josef, Emperor crowned during the year 1848, and the new German Empire were all allies. Yet six later this went horribly wrong.