Central Europe was split into large states and
hundreds of tiny entities, each maintaining its independence with the assistance of outside powers, particularly
Austria, the personal territory of the
Habsburg Emperors, was traditionally considered the leader of the German states, but
Prussia was becoming increasingly powerful and by the late 18th century was ranked as one of the
great powers of Europe.
Francis II's abolition of the office of Holy Roman Emperor in 1806, intended to prevent
Napoleon from seizing it, also deprived him of his imperial authority over most of German-speaking Europe, though little true authority remained by that time; he did, however, retain control of an extensive multi-ethnic empire after Napoleon's defeat. After 1815, the
German states were once again reorganized into a loose confederation: the
German Confederation, under Austrian leadership.
The pretext for the conflict was found in the dispute between Prussia and Austria over the administration of
Schleswig-Holstein, which the two of them had conquered from Denmark and agreed to jointly occupy at the end of the
Second Schleswig War in 1864. When Austria brought the dispute before the German Diet and also decided to convene the Diet of Holstein, Prussia declared that the
Gastein Convention had thereby been nullified and invaded Holstein. When the German Diet responded by voting for a partial mobilization against Prussia,
Bismarck claimed that the German Confederation was ended.
Crown Prince Frederick "was the only member of the Prussian Crown Council to uphold the rights of the
Duke of Augustenberg and oppose the idea of a war with Austria which he described as fratricide". Although he supported unification and the restoration of the medieval empire, "Fritz could not accept that war was the right way to unite Germany."
Map of Austro-Prussian war
Partly in reaction to the triumphant French nationalism of Napoleon I and partly as an organic feeling of commonality glorified during the
German nationalism became a potent force during this period. The ultimate aim of most German nationalists was the gathering of all Germans under one state.
Two ideas of national unity eventually came to the fore – one including and one excluding Austria.
The US newspaper The New York Times summarized its views of German nationalism shortly after the outbreak of the war:
There is, in political geography, no Germany proper to speak of. There are Kingdoms and Grand Duchies, and Duchies and Principalities, inhabited by Germans, and each separately ruled by an independent sovereign with all the machinery of State. Yet there is a natural undercurrent tending to a national feeling and toward a union of the Germans into one great nation, ruled by one common head as a national unit.
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There are many interpretations of
Otto von Bismarck's behaviour before the Austrian-Prussian war, which concentrate mainly on whether he had a master plan that resulted in this war, the North German Confederation and the unification of Germany. Bismarck maintained that he orchestrated the conflict in order to bring about the North German Confederation, the Franco-Prussian War and the eventual unification of Germany. However, historians such as
A. J. P. Taylor dispute his interpretation and believe that Bismarck did not have a master plan, but rather was an opportunist who took advantage of the favourable situations that presented themselves. Taylor thinks Bismarck manipulated events into the most beneficial solution possible for Prussia.
On 22 February 1866, Count Karolyi, Austrian ambassador in
Berlin, sent a dispatch to the Minister of Foreign Affairs,
Count Alexander Mensdorff-Pouilly. He explained to him that Prussian public opinion had become extremely sensitive about the Duchies issue and that he had no doubt that "this artificial exaggeration of the danger by public opinion formed an essential part of the calculations and actions of Count Bismarck [who considered] the annexation of the Duchies ... a matter of life and death for his political existence [and wished] to make it appear such for Prussia too."
Possible evidence can be found in Bismarck's orchestration of the Austrian alliance during the
Second Schleswig War against Denmark, which can be seen as his diplomatic "masterstroke". Taylor also believes that the alliance was a "test for Austria rather than a trap" and that the goal was not war with Austria, contradicting what Bismarck later gave in his memoirs as his main reason for establishing the alliance. It was in the Prussian interest to gain an alliance with Austria to defeat Denmark and settle the
issue of the duchies of Schleswig and Holstein. The alliance can be regarded as an aid to Prussian expansion, rather than a provocation of war against Austria. Many historians believe that Bismarck was simply a Prussian
expansionist, rather than a German nationalist, who sought the unification of Germany. It was at the
Gastein Convention that the Austrian alliance was set up to lure Austria into war.
Bismarck made an alliance with Italy, committing it to the war if Prussia entered one against Austria within three months, which was an obvious incentive for Bismarck to go to war with Austria within three months to divert Austrian strength away from Prussia. The timing of the declaration was perfect, because all other European powers were either bound by alliances that forbade them from entering the conflict, or had domestic problems that had priority. Britain had no stake economically or politically in war between Prussia and Austria. Russia was unlikely to enter on the side of Austria, due to ill will over Austrian support of the anti-Russian alliance during the
Crimean War and Prussia had stood by Russia during the
January Uprising in Poland whereas Austria had not.
France was also unlikely to enter on the side of Austria, because Bismarck and
Napoleon III met in Biarritz and allegedly discussed whether or not France would intervene in a potential Austro-Prussian war. The details of the discussion are unknown but many historians think Bismarck was guaranteed French neutrality in the event of a war. Italy was already allied with Prussia, which meant that Austria would be fighting both with no major allies of its own. Bismarck was aware of his numerical superiority but still "he was not prepared to advise it immediately even though he gave a favourable account of the international situation".
When the Prussian victory became clear, France attempted to extract territorial concessions in the
Luxembourg. In his speech to the
Reichstag on 2 May 1871, Bismarck said:
It is known that even on 6 August 1866, I was in the position to observe the French ambassador make his appearance to see me in order, to put it succinctly, to present an ultimatum: to relinquish
Mainz, or to expect an immediate declaration of war. Naturally I was not doubtful of the answer for a second. I answered him: "Good, then it's war!" He travelled to Paris with this answer. A few days after one in Paris thought differently, and I was given to understand that this instruction had been torn from Emperor Napoleon during an illness. The further attempts in relation to Luxemburg are known.
Unpopular rulers sought foreign war as a way to gain popularity and unite the feuding political factions. In Prussia King William I was deadlocked with the liberal parliament in Berlin. In Italy King
Victor Emmanuel II faced increasing demands for reform from the Left. In Austria
Emperor Franz Joseph saw the need to reduce growing ethnic strife by uniting the several nationalities against a foreign enemy.
Memorial to Battery of the Dead at Chlum commemorates some of the heaviest fighting during
Battle of Königgrätz
(3 July 1866)
Bismarck may well have been encouraged to go to war by the advantages of the Prussian army against the Austrian Empire. Taylor wrote that Bismarck was reluctant to pursue war as it "deprived him of control and left the decisions to the generals whose ability he distrusted". (The two most important personalities within the Prussian army were the War Minister
Albrecht Graf von Roon and Chief of the General Staff
Helmuth Graf von Moltke.) Taylor suggested that Bismarck was hoping to force Austrian leaders into concessions in Germany, rather than provoke war. The truth may be more complicated than simply that Bismarck, who famously said that "politics is the art of the possible", initially sought war with Austria or was initially against the idea of going to war with Austria.
Rival military systems
In 1862, von Roon had implemented several army reforms that ensured that all Prussian citizens were liable to conscription. Before this date, the size of the army had been fixed by earlier laws that had not taken population growth into account, making conscription inequitable and unpopular for this reason. While some Prussian men remained in the army or the reserves until they were forty years old, about one man in three (or even more in some regions where the population had expanded greatly as a result of industrialisation) was assigned minimal service in the
Landwehr, the home guard.
Introducing universal conscription for three years increased the size of the active duty army and provided Prussia with a reserve army equal in size to that which Moltke deployed against Austria. Had France under Napoleon III attempted to intervene against the Prussians, they could have faced him with equal or superior numbers of troops.
Prussian conscript service was one of continuous training and drill, in contrast to the Austrian army where some commanders routinely dismissed infantry conscripts to their homes on permanent leave soon after their induction into the army, retaining only a cadre of long-term soldiers for formal parades and routine duties.
 Austrian conscripts had to be trained almost from scratch when they were recalled to their units on the outbreak of war. The Prussian army was thus better trained and disciplined than the Austrian army, particularly in the infantry. While Austrian cavalry and artillery were as well-trained as their Prussian counterparts with Austria possessing two elite divisions of heavy cavalry, weapons and tactics had advanced since the
Napoleonic Wars and cavalry charges had been rendered obsolete.
Speed of mobilization
The Prussian army was locally based, organised in Kreise (military districts, lit.: circles), each containing a Korps headquarters and its component units. Most reservists lived close to their regimental depots and could be swiftly mobilised. Austrian policy was to ensure that units were stationed far from home to prevent them from taking part in separatist revolts. Conscripts on leave or reservists recalled to their units during mobilization faced a journey that might take weeks before they could report to their units, making the Austrian mobilisation much slower than that of the Prussian Army.
Speed of concentration
The railway system of Prussia was more extensively developed than that within Austria. Railways made it possible to supply larger numbers of troops than hitherto and allowed the rapid movement of troops within friendly territory. The better Prussian rail network allowed the Prussian army to concentrate more rapidly than the Austrians. Moltke, reviewing his plans to Roon stated, "We have the inestimable advantage of being able to carry our Field Army of 285,000 men over five railway lines and of virtually concentrating them in twenty-five days. ... Austria has only one railway line and it will take her forty-five days to assemble 200,000 men."
 Moltke had also said earlier, "Nothing could be more welcome to us than to have now the war that we must have."
The Austrian army under
Ludwig von Benedek in
Bohemia (the present-day
Czech Republic) might previously have been expected to enjoy the advantage of the "central position", by being able to concentrate on successive attacking armies strung out along the frontier, but the quicker Prussian concentration nullified this advantage. By the time the Austrians were fully assembled, they would be unable to concentrate against one Prussian army without having the other two instantly attack their flank and rear, threatening their lines of communication.
Armaments and tactics
Prussian infantry were equipped with the
Dreyse needle gun, a bolt-action rifle capable of far more rapid fire than the
Lorenz rifles of the Austrian army. In the
Franco-Austrian War of 1859, French troops had taken advantage of the fact that the rifles of the time fired high if sighted for long range. By rapidly closing the range, French troops could come to close quarters without sustaining too many casualties from the Austrian infantry. After the war, the Austrians had adopted the same methods, which they termed the Stoßtaktik ("shock tactics"). Although they had some warnings of the Prussian weapon, they ignored these and retained Stoßtaktik. The Austrian artillery had breech-loading rifled guns, while the Prussian army retained many muzzle-loading smooth bore cannon. New
Krupp breech-loading cannons were only slowly being introduced but the shortcomings of the Austrian army prevented the artillery from being decisive.
The Battle of Königgrätz.
In 1866, the Prussian economy was rapidly growing, partly as a result of the
Zollverein, which gave Prussia an advantage in the war. Prussia could equip its armies with
breech-loading rifles and later with new Krupp breech-loading
artillery but the Austrian economy was suffering from the effects of the
Hungarian Revolution of 1848 and the
Second Italian War of Independence. Austria had only one bank, the
Creditanstalt and the state was heavily in debt. Historian
Christopher Clark wrote that there is little to suggest that Prussia had an overwhelming economic and industrial advantage over Austria and wrote that a larger portion of the Prussian population was engaged in agriculture than in the Austrian population and that Austrian industry could produce the most sophisticated weapons in the war (rifled artillery). The Austro-Prussian War ended quickly and was fought mainly with existing weapons and munitions, which reduced the influence of economic and industrial power relative to politics and military culture.