|This article covers a war or battle
The Hohenzollerns' War (La Guerre de 1870 in France, La Guerra del Rey Leopoldo in Spain) was a conflict that happened in the year 1870 after Prussian prince Leopold zu Hohenzollern-Sigmaringen was declared King of Spain by the Spanish Courts. France would declare war on Spain and Prussia after both rejected France's ultimatum.
On September 1868, the Spanish liberals conspired to dethrone Queen Isabel II, as they considered that Spain's only way to become great once more was through the liberalization and democratization of the nation. After a short revolution nicknamed La Gloriosa by the Spanish people, a Provisional Government took the reigns of Spain, and started to develop the nation. The Spanish Constitution of 1869 declared Spain to be a Constitutional Monarchy, but there was the problem that finding an adequate prince to take the Spanish Crown was far more difficult than what it was thought.
Meanwhile, Prussia was in the middle of trying to unify all the small German nations around her, to create a German Empire led from Berlin. This was thanks to Prussian Chancellor Otto von Bismarck's titanic efforts to do so. Bismarck had already achieved the formation of the Northern German Federation (NGF), but he had yet to attract the attention of the Southern German states of Baden, Bavaria, Hesse and Württemberg. However, the NGF had signed secret defensive alliance pacts with the four Southern German nations, so, if someone declared war on Prussia, the Southern Germans would join on Prussia's side. Bismarck hoped that, when France declared war, the post-victory euphoria would be so great that the German people would demand the final unification of Germany into one great empire.
France, in the meantime, was very interested in the election of the Spanish king, as Spain was an ally of France and several of the candidates (especially the Duke of Montpensier, who also was a pretender of the French Crown) were disliked by Napoleon III, Emperor of France. This was compounded with France's diplomatic isolation, due to several French foreign policy mistakes, as they either supported those who were against potential allies or did not act when they were required. So, the only potential allies France had at the time were Spain and the United Kingdom, and the latter was more concentrated in its own Empire than in the comings and goings of the Continent.
The initial cause of the war was the Spanish Courts' election, as King of Spain, of Leopold zu Hohenzollern-Sigmaringen. These news caught the French on a wrong foot, since they did not have an idea that Leopold was even being considered, so the French immediately demanded Leopold's renounce to the Spanish throne. Although for a moment it looked like they would achieve their objective, French hubris made them demand King Wilhelm I of Prussia for a written and signed confirmation that neither Leopold nor other Prussian prince would be considered for the Spanish crown. The encounter would be communicated by the King to Bismarck by telegram, and Bismarck decided to slightly modify it and publish it in the main Prussian newspapers, which fired the anger of both Prussians and French. The latter would immediately give an ultimatum: either the King apologized and promised that no Prussian prince would be candidate to the Spanish crown, ever, or France would declare war. Prussia and Spain rejected the ultimatum, and France declared war on July 20th 1870.
Knowing that the events would eventually catch up with them, and that it was better to be safe than sorry, Juan Prim, then President of the Council of Ministers of Spain (official title for the Prime Minister), ordered a mobilization order on July 9th to prepare Spain for war. Two armies of approximately 100,000 soldiers each were deployed near the two passes between Spain and France that allowed for the passage of great numbers of troops, La Junquera (Eastern Pyrenees, near the Mediterranean Sea), where the Spanish troops would be led by Juan Prim; and Fuenterrabía (Western Pyrenees, near the Cantabric Sea), where the troops would be led by Francisco Serrano. Several thousands of more troops led by Manuel Pavía y Rodríguez were also ready for a potential invasion of French Algeria. The Spanish Home Fleet was divided in three: one fleet would be under control of Admiral Juan Bautista Topete, and would cover Juan Prim's advance; the second would be under control of Admiral Luis Hernández-Pinzón; and a third would be controlled by Admiral Claudio Alvargonzález, who would help protect the Mediterranean coast and perhaps initiate the invasion of French Algeria. Serrano's troops could also count with the help of several Carlist requetés, guerrilla troops which had dropped their allegiance to Carlos María de Austria y Borbón-Este (the Carlist pretender, self-styled Carlos VII) after he had asked Napoleon III to invade Spain and place him as the King of Spain.
France's mobilization order arrived on July 16th. The mobilization was chaotic, especially after war was declared, as movement of troops was rushed across France and several times the soldiers arrived to their destinations without the required equipment while others had to await for their train. The recent experience of Algeria also affected their deployment, and lines of defensive fortifications were placed near the frontlines. In the end, 350,000 soldiers, led by Napoleon III and Marshals Patrice de MacMahon and François Bazaine, had formed in the border with Prussia, while 75,000 soldiers were placed in front of both La Junquera and Fuenterrabía: the former were led by Louis Jules Trochu, and the latter by François Certain-Canrobert. The French fleet was tasked with blockading the German coast and protecting the French coast from Spanish naval attacks.
Prussia initiated its mobilization on July 19th. Their mobilization was much faster than that of the French, as well as better organized, thanks to the Prussian General Staff and the organization of the railway timetables, so that soldiers could arrive to their positions at the correct times. Much sooner than others would have expected, the Prussians had already deployed 450,000 soldiers to the frontline, including the allied contingents. Their fleet would, unfortunately, be unable to do much, because its size was very much smaller than France's, but it was expected that it would be able to, at least, defend Germany's coast.
The war properly started on August 8th: the French, ready to smash the German armies, invaded through the common French-Prussian border and took the city of Saarbrücken after a short battle. However, Prussian General Helmuth von Moltke and Otto von Bismarck had realised since war was declared that the French would attack there, so they had already placed their armies in positions that took advantage of the French moves, and, after victories in Wissembourg on the 10th and Spicheren on the 12th, all French troops had been forced back through the border.
Meanwhile, things in the Pyrenees Front were going more in favour of France: although the invasion through La Junquera into Catalonia had failed, Canrobert's army managed to defeat Serrano's, who was forced to retreat on the 12th towards Vitoria, allowing Canrobert to take San Sebastián two days later. He would soon continue his attacks on Spanish positions nearby, although the Carlist requetés attacked them constantly in a reminder of the Spanish guerrillas that made French troops' life impossible during the Spanish Independence War. Juan Prim's troops would soon counter-invade southern France, trespassing La Junquera.
On August 18th (nicknamed "The Day of Balance") the French troops under MacMahon suffered a terrible defeat at the hands of the army led by Kronprinz (heir to the Prussian throne) Friedrich, but Trochu managed to stop Prim through stalemate in the First Battle of Perpignan, and Canrobert defeated Serrano's army again, forcing him to return to Vitoria, which was soon put under siege.
In that moment, Alfonso de Borbón, son of former Queen Isabel II, returned to French-occupied Spain and was named Alfonso XII de España in an attempt to get the support of the Spanish population, but this was met with scorn by most of the population, who were reminded of the Bayonne Abdications.
On August 20th, the French frigate Guérriere managed to avoid Topete's ships and bombarded Barcelona. This fired up the Republicans, who demanded for Spain to get out of the war and the proclamation of a Spanish Republic, but their revolt was stopped on the next day thanks to the efforts of Sagasta's government, as well as those of Eugenio de Gaminde and Lorenzo Milans del Bosch, General Captains of Catalonia and Castile. That same day, Prim was defeated in Ceret and forced to retreat back into Spain.
On August 22nd, French troops under Bazaine were soundly defeated in Mars-la-Tour, which was followed two days later by another defeat in Gravelotte, opening the German army's way to Paris. In between the two French defeats, Vitoria had fallen to the French troops, with Serrano barely escaping the city on time. The French government ordered Canrobert to stop his advance and to send troops to the Eastern Front.
This gave Spain a second wind, and a new army recruited by Serrano managed to liberate Vitoria on the 26th. Prim would invade France again and defeated Trochu's troops on the 27th, taking Perpignan. On September 3rd, Prim defeated Trochu near Carcassonne, and Serrano expelled the French from San Sebastián, to later expel them (and Alfonso XII) from Spain in the Battle of Irún of September 7th.
Those days, Napoleon III decided to start a great battle with which he hoped to destroy the German armies and lift the siege in Metz, where Bazaine was resisting. However, his withdrawal towards Sedan fell into Moltke's plans, and soon Sedan itself was besieged. Things turned confusing as orders and counterorders were given, and the German artillery attacked the French positions. In the end, in order to save his son Louis Napoleon, the French Emperor launched a charge against German positions, dying on September 7th 1870.
Louis Napoleon would be soon crowned as Napoleon IV, and his mother, Empress Eugénie, tried to make peace, but the Spanish-German alliance demands were considered too big and war continued.
In one of the most impressive maneuvers made during the war, on September 20th Spanish Marine Infantry troops landed near the city of Orán thanks to Admiral Alvargonzález's protection, establishing a beachhead that would be used by General Pavía to take the city five days later.
On the 24th, Italian troops entered Rome, putting an end to the Papal States and unifying the whole Italian Peninsula under one flag, with its capital in Rome. Soon, the Italians were asking its government for a declaration of war against France, in order to retake Nice and Savoy (which had been ceded to them after two referenda in 1860) and Corsica (sold by Genoa to France some time before Napoleon Bonaparte was born).
Bazaine's surrender on October 30th, compounded with continuous defeats on land, made it clear that France's time had ended, and that it was better to surrender before they could lose more land. The definite armistice would be signed on November 15th in the Versailles Palace.
The initial consequence of the war was the proclamation of the German Empire, with Wilhelm I as its Emperor, in the Versailles Palace, after the signing of the definite armistice. Leopold would be finally crowned on December 12th in Madrid, after swearing the Spanish constitution. The next was the Treaty of Frankfurt, which put a definite end to the Hohenzollerns' War. The treaty established the following terms:
- France recognizes being the only responsible nation for the war that ends with this peace treaty.
- France recognizes Leopold of Hohenzollern-Sigmaringen as legitimate King of Spain.
- France recognizes the foundation of the German Reich, with William I of Prussia as the new German Kaiser under the name of William I of Germany.
- France recognizes the following territorial changes.
- The regions of Alsace (save for the Belfort territory) and Lorraine become part of the sovereign territory of the German Reich.
- The departments of Eastern Pyrenees (Rousillon) and of Oran (Oranesado) become part of the sovereign territory of Spain.
- The people residing in the regions whose sovereignty has changed will have until January 1st 1873 to decide whether they wish to keep their French nationality and leave for France or remain in the region and become German or Spanish citizens, in accordance to the region. Children will have the same nationality as their parents.
- A suitable frame for the withdrawal of German and Spanish troops from certain zones will be established.
- The Empress Dowager of France, in the name of her son Napoleon IV, transfers his dynastic rights over the Princedom of Andorra to Leopold of Hohenzollern-Sigmaringen and his heirs.
- France will compensate, in respect of war damages to both the German Reich and Spain, a quantity of 5,500 millions of francs to each country, along a period of time not longer than 15 years.
- Military occupation of certain zones of France by German and Spanish forces will be kept until the payments are satisfied. Costs are to be paid by the occupied country, without attributing those to the demanded compensation.
- The use of navigable channels in connection to European regions lost by France is regularized.
- Trade between France on one side and the German Empire and Spain on the other side is regularized.
- The return of prisoners of war is regularized.
Since it was signed on December 24th, the Treaty of Frankfurt was nicknamed le charbon du Pére Noel.
A month after the treaty was signed, the instability in France gave way to a Republican revolt against Napoleon IV, who was exiled to the United Kingdom. The Third French Republic was established, but the new-born Republic was unstable, and three years later it gave way to a new Kingdom of France, with Philippe VII as the new king.
The enthusiasm of the victory, and annexation of old Spanish lands from the French, became the backdrop against which Prim, Serrano and the other democratic leaders organized the National Union Party, which would strengthen Spain until democracy was well rooted. However, the war in Cuba was still going on, and much had to be changed in order for Spain to succeed. Another consequence was that the experience of this war would eventually help create the Tercios Especiales.
Things proceed more or less like in OTL, but with a stronger position, economically and politically, thanks to the alliance with Spain.