Franco-Austro-Prussian War
Battle of Koniggratz by Georg Bleibtreu Battle of Königgrätz, by Georg Bleibtreu. Oil on canvas, 1869.

14 June 1866


25 August 1866 (Armistice)


Bohemia, Germany, Italy and Adriatic Sea


Treaty of Frankfurt


German Confederation:
Austrian Empire
Kingdom of Saxony
Kingdom of Hanover
Reuss Elder Line
Free City of Frankfurt

French Empire

Kingdom of Prussia
Kingdom of Italy
Saxe-Coburg and Gotha


Franz Joseph I of Austria
Albrecht von Österreich-Teschen
Ludwig von Benedek

Napoleon III of France

Wilhelm I of Prussia
Helmuth von Moltke
Victor Emmanuel II of Italy


German Confederation (including Austria): 600,000
French Empire: 300,000

Prussia and German allies: 500,000
Italy: 300,000

Casualties and Losses

Austria: over 130,000
France: 55,000

100,000 dead or wounded (German and Italian)

The War of 1866 was started at the instigation of the expansionist Prussian Chancellor, Otto von Bismarck. It initially pitted Prussia against Austria and the bulk of the German Confederation. Despite initial victories in Bohemia and Lower Austria, the Prussian Army became bogged down in the vicinity of Vienna, as an unexpected enemy entered the fight.


Otto von Bismarck's dream of a Prussian-dominated Germany was on the verge of fulfillment. since the Second Schleswig War of 1861, war bells had been ringing between the victorious allies - Prussia and Austria. Bismarck had exploited their historic animosity for all it was worth, and now conflict between the two powers seemed inevitable.

Bismarck's Prussia was an upstart state, challenging Austria's four-century long domination of the German states. Though the Austrian-dominated Holy Roman Empire had been dissolved generations earlier, the Austrian Emperor still held the title of President of the German Confederation. Bismarck viewed the Confederation as a tool to extend Austrian power indefinitely over Germany, and knew that war was the only means to topple her from her lofty perch.

Still, success in the war was no certainty. It was true that Prussia was better equipped and showed better command of tactics than the Austrian Army. But the Prussian Army was outnumbered, and if any of the other powers allied to Austria, all of Bismarck's plans would fall apart.

However, this scenario seemed unlikely. The other great powers were Britain, France and Russia. Britain had maintained isolation from European affairs since the Crimean War of the 1850s. France had fought Austria in battle less than a decade before on the plains of Italy. And the Russian Emperor, far too interested in gobbling up Turkish territory in the south, would likely see no interest in lending a hand.

Koniggratz Campaign

It was thus that the Kingdom of Prussia declared war on Austria on 14th June, 1866. Under the guidance of the brilliant General Helmuth von Moltke, the Prussian Army concentrated on the Bohemian border with shocking speed, utilising Prussia's extensive rail network. Austrian forces mobilized in the north were therefore unprepared when Moltke's three armies surrounded and destroyed them in the climactic Battle of Koniggratz.

Bismarck, and indeed most of Europe, assumed that Austria would give up the fight at this stage rather than risk losing more territory, and perhaps even its capital Vienna. What Bismarck didn't count on, however, was the opportunism of the man pulling the strings hundreds of miles away in Paris.

The French Element

As the Prussian forces in Bohemia closed in on the Austrian Army, the French ambassador at Vienna asked for an audience with the Emperor, Franz Josef I. At the Schonbrunn, Jean-Picquard Villars informed the Emperor that Napoleon III had weeks ago ordered the mobilization of the French Army, which was nearly complete. If an alliance could be agreed upon, French troops would swiftly invade the Prussian territory on the Rhine and march east on Berlin, threatening the rear of Moltke's army. In return, Napoleon III asked to be granted most of the Prussian Rhineland.

With his army still undefeated, Franz Josef would never have accepted such an offer. To give France the Rhine's left bank once again would in the long-term be just as much of a threat to Austria's position in Germany as Prussia was now. The Austrian diplomats offered instead a few border towns, but the French ambassador had been told to be adamant in his demands. Negotiations, therefore, stalled.

However, all of Austria's equations were soon to be overturned. With the destruction of the main Austrian Army at Koniggratz, the Empire was on the verge of total defeat. The French diplomats urged the Austrian government to fight on. If Austria could tie down the Prussian troops just a few weeks more, France could win the war for them. All they asked for was a reasonable slice of enemy territory.

Napoleon III had given Franz Josef a desperate hope to cling on to. On 10th July, a treaty was signed, and messengers raced back to France to bring the good news to their Emperor.

As the Austrian High Command laboured to pull together as many men as possible to defend Vienna, Napoleon's men were already marching to the Prussian border. In Vienna, the disparate army of Germans, Hungarians, Croats, Italians and Poles dug entrenchments, built shoddy earth walls, and gathered as much food and ammunition into the cities depots as possible. On 22nd the Prussian advance guard reached Vienna's outskirts and the siege began.

French Intervention

Nevertheless, the war at this stage had already been decided. A day earlier, the 250,000 strong Army of the Rhine had crossed into Prussian territory, led by the best generals the French Empire had to offer. Prussian forces had been pulled from the Rhineland to assist the invasion of Austria, and therefore the French found themselves up against just 20,000 shocked young men. Surrounding the isolated units, the French crossed the Rhine in just three days and marched on into Hanover, where 15,000 Prussians beat a swift retreat towards Berlin. The Army of the Rhine did not hesitate, and by the 5th of August had drawn within 3 days' march of the capital.

At the outset of the French offensive, the Prussian government and General Staff were disbelieving of the cataclysm which had befallen them. However, as matters became clearer, Bismarck and Moltke realised that the Prussian Army's positions in Austria were untenable. On the 30th of July, the Siege of Vienna was lifted, and Prussian forces began pulling back towards Berlin. Meanwhile, the massive Prussian reserve army began to mobilize, a fallback plan as large as the force sent into Austria. The Prussian government believed that the reserves would, even on their own, be able to match the French Army man-for-man. But Bismarck was getting jittery. The Prussian plans for mobilization were in disarray now that the western half of Prussia's territory was under occupation. And the reserves could not match the quality of the French regulars. Nothing was certain except that what would follow would be a long, bloody fight.

Berlin Campaign

Down south, the lifting of the Siege of Vienna freed roughly 70,000 Austrian troops from the capital. In addition, French involvement in the war persuaded the Kingdom of Italy to seek an armistice, freeing more than 70,000 Austrians from the theatre. Combined with a variety of forces mobilized from throughout the empire, there were now over 150,000 Austrians in the field.

In ideal circumstances, the Prussian commander Helmuth von Moltke would have preferred to strike at the Austrians as swiftly as possible. He could still bring 180,000 men to the fight, easily outnumbering and outclassing the Austrian force. However, matters further north precluded such an attack. Berlin would soon be under siege, and his men were sorely needed to defend the capital. Moltke had no choice but to draw back with all due speed.

Meanwhile, Napoleon III moved into Brandenburg with 220,000 men. The main objective for the French Army was to capture Berlin before the men of Moltke's three armies in the south could arrive to defend it. The Prussians, meanwhile, had put together 100,000 reserves. Instead of fighting in the streets of Berlin, which would surely reduce the capital to rubble, the reserve army was ordered to defend the line of the Elbe. This battle would be Prussia's final stand.

Moltke's military genius would prove to have been sorely missed in the planning for the defense of Berlin. Though more reserves were being mobilized everyday, their numbers were not sufficient to defend the entire line of the Elbe. Napoleon's army had dozens of crossings at their disposal all along the hundreds of miles of river. Concentrating the army at a single crossing point would shatter the thin Prussian cordon. It was exactly what they would do.

Napoleon was no great military mind, but he knew to listen to his generals' advice. He thus ordered the concentration of the French Army at Magdeburg, southwest of Berlin. On the 3rd of August, the Grand Armee crossed in force at Magdeburg over five bridges and pulverized the Prussian defenders. The reserve army's southern flank had been turned, and Moltke's armies in Austria - escorted by the king himself - were cut off from Berlin. Three days later, Napoleon invested Berlin with five corps, completely surrounding the capital from all sides. Two corps were posted south in order to forestall the arrival of Moltke. But as events would prove, even this precaution was not needed.

Retreat to Berlin and Battle of Tabor

Moltke's retreat, made more crucial by the presence of King Wilhelm himself, was proving to be no easy affair. All along the exposed lines of communication leading back through Bohemia and Saxony, Austrian probed and prodded the evacuating Prussians. Food and ammunition was increasingly scarce as the French cut them off from Berlin, severing the Prussian Army's main supply line. As their movements slowed, Moltke knew that he would eventually have to turn and face the harassing Austrian troops in his rear. If they followed his men all the way back into Brandenburg, Moltke and the king would be truly cornered, with the French pressing from the west and the Austrians from the south.

However, Moltke's mantra of concentrating several separated armies and corps to force a decision could not possibly work as well as well in a defensive battle. The Prussian armies had been following a single line of retreat, and therefore a massive flanking maneuvre like that which had won the day at Koniggratz was unfeasible. On the 10th of August, the Prussian First Army halted its retreat at Tabur, and turned to face the enemy. The Army of the Elbe and Second Army, with some divisions as far away as the outskirts of Prague, were ordered to march back south to assist.

What followed was one of the 19th century's bloodiest battles. In its early stages the battle was a struggle by both sides to concentrate enough men to force a decision. The First Army took a heavy beating in the initial fighting, facing the bulk of the Austrian forces alone. As the day wore on, more Prussian reinforcements joined the battle, the individual corps of the other Prussian armies rushing south as swiftly as possible. The Austria army had the advantage of numbers, but the earlier stages of the war had robbed it of its heavy guns and many experienced veterans. Prussia's superior Dreyse needle gun far outclassed its Austrian counterpart, and Moltke's men were better trained to boot.

In the end, these factors tipped the scales in Prussia's favour. Trusting in their weight of numbers, the Austrians mounted wave after wave of infantry charges against the Prussian lines. Though they gained some early success when the First Army fought alone at Tabor, the arrival of fresh troops reversed the situation, and by evening the Prussians were in position to mount a counterattack that could devastate the demoralised Austrians. However, their single line of operations did not allow Moltke to launch the sort of flanking maneuvre that could have trapped the Austrians and wiped out their army. The Emperor's troops thus withdrew more or less in good order.

Moltke had won a tactical victory. But the losses incurred were heavy, and his retreat into Brandenburg was delayed by several days - days that eventually cost Prussia the war.

The Fall of Berlin

On the 13th of August, with the remaining Prussian reserves mopped up in Brandenburg and serious Polish civil unrest in Posen tying down many Prussian troops, the time was right to strike the decisive blow. Only 20,000 defenders were left in Berlin, no match for the 180,000 Frenchmen bearing down on them. After some heavy initial fighting which devastated parts of the Berlin suburbs, by the third day of the assault the Prussian commanders surrendered in person to Napoleon III.

Magdeburg Campaign

Otto von Bismarck, forever the pragmatist, now began fervently beseeching his king to ask for an armistice. In his view, the sheer weight of numbers stacked against them was insurmountable, and ending the fight now would give them a better position at the bargaining table.

Of course, this was advice that could not be followed. To surrender while Prussia's three main armies remained undefeated would be the greatest humiliation they could possibly suffer. Memories of the Napoleonic drubbing suffered all those years past had yet to fade. They had to fight on. After all, as many had said, Prussia was a military with a state, not a state with a military.

Bismarck's voice could not shout down the clamor among the generals to fight on. But apart from the field armies making their way back to Brandenburg, the morale of the Prussian forces was swiftly disintegrating. For the second time in sixty years, a man named Napoleon had swept into Berlin. The irony was plain to all and painful to most. All across the land Prussian garrisons were surrendering to the French, like they had in 1806. There was no longer an effective high command, as communication from Moltke and the king was thoroughly cut off. The three armies headed north were effectively rebels trying to win back their homeland.

Bismarck knew there was one hope - Russia. Russia was as always the unknown element. France had, after all, gone to war with Russia just a decade prior. Surely they would consider throwing in their lot with France's enemies.

The Russians did consider it. But the Tsar was as usual thoroughly uninterested in European affairs. In the War of 1866 he saw only a chance to use the distraction to seize land from Turkey in the south. Prussia, it seems, was not high on his list of priorities.

So the Prussian Armies trundled on. Helmuth von Moltke's newly improvised plan needed the men to strike west of Berlin and threaten enemy communications. Surprise, it was hoped, would win them a battle. These plans were complicated by the fact that French troops by now occupied Saxony, directly on the line of retreat. Moltke's backhanded swipe was becoming more of a dull head on blow.

The French had already been concentrating towards the south in preparation for Moltke's return. On the 15th, some French scouts reported the Prussian main body bypassing Dresden to the east, making for Magdeburg on the Elbe. At once the French army corps wheeled towards their target. One swift blow, as their first emperor once said, will end the war.

Napoleon III was anxious that he should make full use of his numerical superiority in the upcoming battle, pulling troops from their advance positions west of Berlin. They would prove to be needed.

On the 20th, the Prussian advance guard crashed into the French line at Magdeburg. At this stage only the French I and III Corps were concentrated at Magdeburg, due to uncertainty over Moltke's true intentions. But by the afternoon a further five French corps were joining the fight, crossing the Elbe into the thick of battle.

The attack at Magdeburg failed to achieve full surprise. All the men France needed to hold the town were a few hours' march away. By the end of the first day the Prussians had ground to a halt. Napoleon III had 190,000 men across the bridges into Magdeburg by day's end. There seemed little hope for Moltke and his remaining 130,000.

Amazingly, the morning of the 18th saw a furious Prussian assault. Moltke had during the night realised that pretty much the entire French Army had crossed to the Elbe's left bank to fight his men. This gave Moltke the desperate hope that his army could cross to the other side and separate the French from Berlin, carrying out a lightning march to retake the capital.

It is an indication of Prussia's desperate situation that this was the best plan available to them. It was, in any case, utterly hopeless. Though for a time the Prussians managed to hold the nearest bridge and send a division across, the French reserve was well suited to deal with the threat, and more French reinforcements were marching to the battle from all over the countryside. The Prussian assault was broken, and now the French went on the attack. Prussian morale had been shattered, and the battle became a complete rout. King Wilhelm fled with his men, until at a safe distance he regrouped his advisers and composed his armistice plea. The war was effectively over.

Treaty of Frankfurt

Napoleon III and Austria dictated the terms of peace to Prussia at the Conference of Frankfurt. The treaty saw the end of Prussia's military dominance, reducing it for the foreseeable future to the status of second-rate power. It also defined the new status quo in Germany and Italy.

Start a Discussion Discussions about War of 1866 (Rise of the Second Empire)

  • Bad Writing Strategy

    5 messages
    • Nonsense, those minorities were an extremely big problem for Austria: C. Speed of mobilization Austro-Prussian War: "the Austri...
    • Incorrect. It wasn't until the 1880s where the minorities, barring the Hungarians, became a problem - and the Hungarians were only one af...

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