Prussia conquered Germany without multiple powers banding together against them. But what if this wasn't the case? I envision two scenarios: a) The Austro-Prussian war escalates. France and/or Russia intervenes. It is worth bearing in why they didn't- Russia was to continue to focus on the Black Sea and gain a "friendly" stronger neighbour in Prussia (they were still bitter over Austrian intervention in Crimea) and France was promised some vague bit of the Rhineland and Napoleon III saw Austria as the key enemy. Maybe Napoleon III would be assassinated and France pursued a sane foreign policy? b) The Franco-Prussian war escalates. Perhaps the peace settlement with Austria would have been harsher, and therefore Austria signs an agreement with France? Perhaps Russia sees the clear and present danger and intervenes? Would Britain ally with Germany (despite the fact Disraeli correctly identified it would harm her position the most) to stop a French/Russian victory? Who would win? If anyone is a military historian, perhaps they could help (I know very little about military policy, but I do know about political history) P.S.- It is conceivable that the Danish war would have escalated also, but less likely (the British might save the key location as a method of containing Prussia, I guess) UPDATE 1: Summary post on 1870 timeline (I know @Mrfanboy also came up with a list, I'm just using this one because it has explanations on it: From what I can see, there are two clear blocks: Prussian block: Prussia (Franco-Prussian War) Russia: Austrian involvement convinces them to seize the initative in the Balkans by weakening Austria- they smell weakness by Hungarian insurrection and the failure of the compromise of 1867 following Austrian involvement, because the Hungarians believe the war is a ploy to roll back the Hungarian compromise. Hoping to gain Galicia and a free hand in the Balkans. Possible members: Britain (I think this is unlikely, but some have argued otherwise. Prussian expansionism did not sit well with British public opinion. The Russo-Prussian alliance means that the English probably wouldn't join, as it would directly enable Russian expansion- after Crimea, it was paramount for the british to avoid this) Italy (again, I think this is unlikely. They could use the war to seize irredentist claims against Austria and France. BUT they would probably sit neutral to try and extract concessions. Remember, they JUST unified Italy and were keen to garner international acceptance of their Rome annexation, by far the most important. They would not risk it all in a foreign war) French Block France (Franco-Prussian war) Austria (In this timeline, let's say the Treaty of Prague was harsher and Austria was forced to give up Bohemia. Austrian opinion is outraged and they are looking to rectify their position and regain prominence within Germany and undo the humiliation) Possible: The Ottoman Empire- To stop an ascendant Russia in the Balkans Britain- to safeguard the balance of power, both in Germany and in the Balkans (see several earlier posts) UPDATE 2: Summary of 1866 vs 1870 debate, relevant for the poll above. 1866 (Austro-Prussian War). Merits: France would have to intervene, which is much easier than imagining Austria intervening in 1870 Bismarck and others believed there was a real possibility of escalation if the Prussians attempted to march on Vienna. France was apparently ready to join. It's possible that Wilhelm I ignores his advice, Bismarck quits and France intervenes. Wilhelm I and Moltke were both keen on continuing the advance. If Prussia is more seriously pan-nationalist, they may attempt to unite Germany in the course of this war, perhaps with Austrian Germany included. This would certainly stoke French intervention. Cons: As pointed out by @cjc, France was hardly in a shape where it could fight Prussia effectively in 1866. It would be an almighty gamble. Domestic situation within France- Napoleon III did not need a foreign conflict to shore up his position in France, but he certainly did in 1870 (something like 3.3 million votes cast in favour of opposition candidates) Russia would be less likely to intervene than in a Franco-Prussian war, so in terms of "World War" the possibilities of escalation are more limited. 1870 (Franco-Prussian war) Merits: There's a more realistic chance of France holding out for longer, and thus prompting Austrian intervention A harsher treaty of Prague where all of Bohemia (no, I'm not talking about little strips of territory...) is ceded to Prussia or the like, or significant indemnities are incurred, could easily prompt Austrian intervention. Russia might use this opportunity to retake the title of defender of Christians within the Ottoman Empire from Napoleon III, and to neuter Austria as a threat to the sphere of influence (see multitude of earlier posts for clearer explanation). Cons: There is a slight Catch-22 in that Austria can't intervene if the Treaty is too harsh, but wouldn't if the treaty was moderately more severe. I personally don't agree with this; Austria was close to intervening in the OTL, but some have raised this concern Russia might also not intervene (not wanting to help Austria or create a strong Prussian power) UPDATE 22/11: CHAPTER 1: THE WAR BEGINS: ‘The Balkans aren't worth the life of a single Pomeranian grenadier!’- Otto Von Bismarck, 1866. Chapter One of the European Tragedy: The Treaty of Prague. The War with Austria in known as Prussia as the ‘Kriegsprobe’ (War rehearsal) was swift and seemingly decisive, much in contrast of the conflict to come. Engineered by Otto Von Bismarck, this war was intended to drive out Austrian influence in Germany, to make sure that Prussia is not incorporated into some Greater German State. If German unity was to be inevitable, it must unite under Prussia, and not Austria; this war would pave the way for that, whilst making a ‘Kleindeutschland’, where Prussia- and more broadly Prussian Junkers- could dominate, possible. And at first it seemed as if the gamble worked. Although most of the German Confederation lined up against Prussia, Bismarck’s skilful diplomacy kept foreign powers out of the struggle. Prussia’s efficient and disciplined troops crushed the Austrians, already weakened by the 1859, decisively at Sadowa. But it was after that success, only 3 weeks into the war, that ruptures began to emerge. The fruits of victory were showered too fast onto Prussia. The victory at Konnigratz opened the door to the occupation of Vienna, and after all they’d only been at war three weeks. But Bismarck already agitated for a ceasefire. The terms of this ceasefire would see Venetia ceded to Italy and Austria kicked out of German affairs entirely, but not a foot of territory would be taken from the Hapsburgs. The military and monarchical authorities both questioned this; why should Prussia respond to complete victory with such a tepid peace? Moltke was strongly against it and urged the King to continue on his advance. Bismarck implored, pleaded and supplicated; breaking down into tears and smashing objects in the room, Bismarck insisted that the King would be responsible for a horrible and bloody escalation of the war if he was to continue to advance. In what many consider to be the turning points of Prussia’s fortunate, Wilhelm I did not listen. “Any peace with the Austrians must constitute a victor’s peace, not this strange political concoction. It is insulting to Prussian honour to accept otherwise.”. Thus Moltke won out and Prussia pushed for an annexationist war against Austria and decided to continue onto Vienna, much to the incredulity of the French. Bismarck, traumatised and distraught that Wilhelm I had destroyed his intricate plans, was forced to resign. The war continued. the war lasted only a month longer, but it set in motion a horrible chain of events. Wilhelm I got his little occupation of Vienna; the Austrians couldn’t muster enough troops to defend the city. The Prussian march through the city, memorably photograph, was to provide a permeant scar on the honour of the Austrian state. The peace treaty was harsh, both to German states that had so fatefully sided with the Austrians and to oppose Prussian expansion. Saxony and Hanover were annexed into the Kingdom of Prussia, along with Hesse-Kassel, Hesse-Darmstadt, Nassau, Saxe-Meiningen, Frankfurt, Reuss-Greiz, and Holstein. States that backed Prussia were forced into the “North German Confederation”. The South was left broadly alone. Prussia also annexed the “Saxon Corridor from Austria- a strip of territory running across Bohemia which included the town of Karslbad and Austrian Silesia. These are annexed into Prussia as the province of "New Silesia"- harking back to the days of Fredrick the Great. Venetia and some of Istria are lost to Italy. This Treaty caused international outcry. This railroading of tradition and vast annexations suddenly meant that the “lesser Global power” was a threat to national security for the Great Powers, especially France. France was promised a part of the Rhineland which she never received and was infuriated at this vast expansion of Prussian power; although the French army was too weak to intervene in 1866, a series of reforms initiated in 1867 onwards began to stabilise and modernise the army. The Austrian emperor, Franz Joseph, was force to sign the compromise of 1867 under domestic pressure, turning his empire into a dual monarchy. The British were worried by this upstart power too and concerned at the annexation of Hanover. Only Russia seemed to take Prussia’s side; although there were Pan-Slavic objections to this strong German power, their co-operation over Poland had conviced the Tsar that they were a better partner that the Hapsburgs, who had betrayed them in the course of the Crimean War. Moreover the Tsar was more preoccupied with the Balkans that Central Europe, and he knew a weakened Austria would give him a free hand in the Balkans. Prussia and Russia continued to work constructively. By 1869 the French and Austrians have agreed a mutual defence pact, clearly pointing the empires towards war. The French are dead set on containing Prussia; the domestic troubles convincing Napoleon III that he needs a foreign enemy. The situation in Austria is more complex. The Hungarians lobby against war, but German liberals, who are concerned about the triumph of an illiberal Prussia, and aggravate nationalist minority who want to row back the 1867 compromise and rectify national honur after the humiliation of 1867. It’s a hard decision for Franz Joseph, but the pro-war lobby wins out. The territorial loses are too hard to bare; they will be rectified. The large indemnity payment is also causing economic suffering, fuelling worries about a revolutionary collapse of the empire; the common enemy, Prussia, is needed to bring Austria together. The Spark for the war comes from Negotations that attempted to form the German Empire in 1870. The background to the Bavarian crisis was the Spanish Crisis, where a Prussia Hohenzollern was nearly crowned King of Spain, before backing down in the face of French pressure. Tensions were still simmering because Wilhelm I had not given a personal guarantee that he'd never endorse a Hohenzollern candidacy again, but the crisis humiliated Prussia. National opinion with Prussia was outraged. As Moltke commented wryly: "How could a nation that could defeat the Austrian Empire in 6 weeks back down to a Napoleon doppelganger's every little demand?". Wilhelm I was growing increasingly frustrated with the Franco-Austrian demands. And this brings us back to the Negotations with the Southern German states. France made it very clear during 1866 that annexations of these states would lead to war, and thus they were not incorporated into the North German Confederation. But Wilhelm I, needing a victory after the Spanish humilliation, re-opened the issue. A communique sent on the 12th September 1870 to Bavaria and the other Southern German states offered some autonomy (greater than the Northern members) if they'd agree to be part of the German Empire. However, France stepped in. France stated that they were willing to guarantee the independence of the South German states, with Austria adding that "The Austrian government, which has always shared a spiritual connection with fellow Southern German states, stands wholeheartedly in defence of Catholic Germany in response to Northern Prussian aggression". As a result, each of the states rejected membership. This was too much for Prussia. Wilhelm I summed the situation up. "Gentlemen, I will be cowed by the Bonaparte family no longer. For all of my childhood, the French rampaged through our homeland, took our resources and starved us dry. But Prussian honour and ingenuity won the day at the miraculous victories at Leipzig and Waterloo. It was because the German people united together against common aggression, and I believe that spirit still exists. The German people will rise to this challenge. We will not accept Bonaparte's dictat." Thus, after the failure of Negotations at London, Wilhelm I sent troops to occupy Munich, overwhelming the Bavarian forces, helped along by popular support. France declared this an attack upon her people and declared war on the 4th October 1870. Austria followed on the 7th October, saying that it would 'defend to the death the kinsmen of the Austrians', despite Hungarian opposition. The Great European War had begun.