In 1869, a revolution broke out in Spain, and Isabella II stepped down and fled to France. In this regard, Lin Hong and the cabinet also laughed, and earned the advance payment for the purchase of the ship in vain.

In the spring of 1870, Queen Isabella II of Spain, who was in exile in Paris, announced her abdication, and the Spanish government wanted to ask the cousin of the King of Prussia to become king. King Wilhelm I of Prussia objected for fear of angering France, but when Bismarck's success persuaded him to change his attitude.

By 1 July, Spanish newspapers were prematurely disclosed. France believed that German Chancellor Bismarck was deliberately making France suffer from the enemy, so it expressed strong opposition and even declared war on Prussia. In the face of this tension, Wilhelm I was disappointed to Bismarck by suddenly and openly expressing his disapproval of his cousin's succession to the Spanish throne.

On July 13, 1870, the French ambassador to Prussia, Beneddi, with a new directive from the French government, went to the Ames Spa, a place of residence for the King of Prussia, in the eastern suburbs of Koblenz, to ask for an audience with William I, conveying a secret letter from Napoleon III "that His Majesty would guarantee that in the future he would not ask for such a renunciated candidacy". But this impudent attitude shocked William I. Wilhelm I then sent an urgent telegram from Ames to Berlin about the contents of his conversation with the French ambassador.

At this time, Bismarck was holding a family banquet, and suddenly received an urgent telegram from Wilhelm I, after reading the message, Bismarck was very happy, and asked the chief of staff, Moltke, whether he was sure of a complete victory in the French war, Moltke replied in the affirmative. Bismarck then took up his pen and revised the message, deleting the phrase "it is still possible to discuss the long term in Berlin" from the message, and adding at the end the words that provoked France: "His Majesty shall hereafter refuse to receive the French Ambassador, and order the aide-de-camp on duty to convey to the French Ambassador that His Majesty has nothing more to talk about." ”

After Bismarck published this telegram in the newspapers and informed all Prussian missions abroad, the contents of Ames's urgent telegram soon reached Paris, and public opinion was in an uproar, and Napoleon III was enraged. On July 19, 1870, France declared war on Prussia, and the Franco-Prussian War broke out.

The Franco-Prussian War of 1870 was a war that both sides wanted to fight, but the motives for fighting were different. Before the 70s of the 19th century, Germany was in a state of fragmentation for a long time, and its economic development lagged behind that of other European powers. King Wilhelm I of Prussia, the representative of the Junker landlords of Prussia, and Prime Minister Bismarck, were determined to unify Germany by force and realize Germany's dream of European dominance. Therefore, in 1864 and 1866, dynastic wars were waged against Denmark and Austria successively, and the leadership of the unified Germany was obtained, and the North German Confederation was established, which was a crucial step on the road to unification. At this time, the four southern German states (Baden, Hesse, Württemberg and Bavaria) were still on their own side with the support of France.

On the eve of the Franco-Prussian War, the Prussian army, with its universal conscription, was the most powerful in Western Europe. The strength of the North German Federal Army (including the armies of the southern German states) could reach more than 1 million in wartime (including more than 690,000 combat troops). Almost 1 times the strength of the French army. During the war, the armies were organized into several group armies. The German artillery was armed with steel-barreled rifled guns manufactured by the Krupp Arsenal (technology supplied by China), which had an effective firing range of 3.5 km.

The infantry was armed with Shaspo-type pistol breech-loading guns with an effective range of 1,500 meters (0.5 times longer than the German Drezer firing pin guns), and 25 "Mitrayoz" guns (with a rate of fire of 250 rounds per minute and a range of 1,500 meters). However, the French bronze rifled guns were front-loaded, and their range was far inferior to that of the Germans. The French military system does not have a two-level establishment of corps and divisions (except for the Guards) in peacetime, and it is hastily organized in times of war, so it cannot ensure the proper coordination of units (sub-units), and this is a major mistake of the French head of affairs organ. France did not have a well-planned war plan in advance, and the hastily drawn up plan contained many errors, such as the improper time limit for the mobilization and build-up of troops, and the assumption that the German League would disintegrate did not correspond to reality, and so on.

On 19 July, France declared war on Prussia. By the end of July, about 220,000 men had been assembled in eight armies on the border, with Napoleon III as commander-in-chief and Loebf as chief of the general staff. Napoleon III deployed his army in three lines: the first line was the main Rhine corps, with three corps, deployed between Tionville and on the Franco-German border, first under the personal command of the French Emperor and later under the command of Marshal Bazin; The 2nd line consisted of 2 corps, deployed in Strasbourg and Matz, under the command of Marshal McMahon; The 3rd line consisted of 2 corps in reserve, deployed in Nancy and Chalon. This was supposed to be a pre-emptive offensive deployment, with plans to concentrate forces to quickly cross the border and advance towards Frankfurt, cutting off the link between North and South Germany, forcing the South German states to remain neutral and defeating Prussia with all their might. Unlike the French division of the army, the Prussian army was led by Wilhelm I as commander-in-chief and Moltke as chief of the general staff. It was planned to concentrate superior forces and attack Alsace and Lorraine, in an attempt to annihilate the main French army on the Franco-Prussian border or drive it to northern France, and then attack Paris. By the end of July, about 470,000 men from three corps and 1,584 artillery pieces had been assembled on the border.

On 2 August, the French army launched a first offensive against the Prussian army in the Saarbrücken area with three divisions, but there was no vigorous combat action, and only some small contacts were made with the enemy's avant-garde forces. On 4 August, the Prussian army turned to the offensive and crossed the border. The French met the Prussian attack from unfavorable positions in the border area, and the 3rd Army of the Prussian Crown Prince Friedrich Wilhelm defeated the division of the French General Douai at the Battle of Wissanburg with 10 times the number of men (4 August), the French suffered 23% casualties, and on 6 August the two armies fought again at Walter, the French heavy cavalry launched a brave charge, but the 2nd Army of Prince Carl Frederick of the Prussian army had 130,000 men, and the 1st Army of Marshal McMahon was 40,000 men. On the same day, the 2nd Army of General Frossard, France, which belonged to Bazin's legions, was also defeated in Forbach, opening the door to Lorraine.

After the war, there was a period of intermission in the campaign, because the main force of the Prussian army could not be fully deployed, it could not continue to attack and pursue the victory. Although the French army was defeated in the battle in the border area due to insufficient preparation before the war, the main force did not receive a major blow from the Prussian army, and the losses were limited; At the same time, the positions on the border were designed for offensive purposes and were not at all suitable for defense. In this situation, the main force of the French army should have withdrawn to the depth of the theater of operations in a planned manner, replenished troops, adjusted its deployment, and stood by for a decisive battle with the Prussian army. However, the defeat in the first war had immediate political repercussions, with the fall of Emile Olivier and the formation of a government on 10 August by Charles Kuzan Montauban, a 74-year-old man who belonged to the main battle faction headed by the Empress. The Parisian government, regency of the Empress, out of political necessity to maintain its own rule, repeatedly intervened in the operational deployment of the front-line commanders to prevent the front-line troops from retreating deep into the theater of operations; And the Emperor, who was in command at the front, also attached an order to Paris, thus making a big mistake of suffering the fruits of his own suffering. The main Rhine corps, originally commanded by the French Emperor, had initially ordered a retreat to the Chalond barracks in the strategic hinterland, but the Paris government believed that if the army retreated, the capital would rebel and insisted that it should not retreat.

So, on August 9, the Emperor changed his plan, halted the retreat of his troops, and decided to hold Metz at all costs. On 12 August, a sick Napoleon III handed over command of the Rhine Corps to Marshal Bazin. Bazin hesitated, sometimes determined to retreat to Charon to join McMahon, and sometimes determined to defend at Metz. When it was finally decided to retreat to Xialong, the opportunity had been lost, and the Prussian army was near. After the Battle of Marslatul on 14 August and the Battle of Gravolote-Saint-Priva on August 18, both armies showed incredible bravery, the French artillery fire was very fierce, Conrobert and Gerben fought each other, although the Prussian 1st, 2nd and Royal Janissaries suffered heavy losses, but blocked the French retreat, Bazin's corps was surrounded by 7 corps and 3 cavalry divisions (160,000 men) of the 1st and 2nd Prussian Corps in Metz. McMahon led his army (more than 120,000 men, 393 artillery pieces, 76 "Mitrayoz" guns) to retreat to Chalon. He had planned to lure the enemy deep and fight the Prussian army under the city of Paris. The regent, Empress Eugenie, and the Imperial Prime Minister, Charles Kuzan Montauban, Count of Baliqiao, feared that continued retreat would cause unrest or revolution in the country, and the Empress believed that "only the enemies of the Emperor would agree to his return to Paris". On 22 August, a delegation led by Speaker Raul arrived at the Emperor's headquarters, advised the Emperor not to return to Paris, and ordered McMahon to march on Metz. Then the Regency Council in Paris sent a telegram to the Emperor: "If Bazin is not supported, the consequences for Paris will be very bad." Faced with this situation, it is doubtful that the capital will be able to defend itself. So the emperor attached himself to Paris. In this way, the Xia Long Legion embarked on a desperate path of being annihilated in Sedan. McMahon led his army from Reims to Metz on 22 August. At this time, a false news came from Berlin that the Prussian army was determined to advance to Paris in all but the troops besieging Metz. In fact, the Prussian 3rd Army continued to pursue Mac-Mahon's corps, and made a bold detour to the right, cooperating with the newly formed 4th Corps to besiege MacMahon's French army at Sedan along with Napoleon III.

On 1 and 2 September, the Franco-Prussian army fought a decisive battle at Sedan in the Battle of Sedan. On the morning of September 1, the Prussian army occupied Vrizi, Dongsheli and other places, successfully cut off the road for the French army to retreat westward, and blocked the French army from behind. At noon on the same day, the Prussian army also completed the encirclement of the French army and attacked with powerful artillery. In the afternoon, after several unsuccessful attempts by the French army to break out, Napoleon III was sent at 4:30 p.m. to Wilhelm I expressing his willingness to "deliver his sword into the hands of His Majesty." On September 2, Napoleon III formally surrendered to the Prussian army with 83,000 officers and soldiers. In this battle, the French lost 124,000 men, and the Prussian army lost only more than 9,000. France was in an uproar.

At this point, the first phase of the war was over, and on September 4, the bourgeoisie took the opportunity to launch a coup d'état in France, overthrowing the Second French Empire, establishing the French Third Republic, and forming a "government of national defense" headed by General Louis Jules Trochu. At this point, the obstacle to the national unification of Germany was removed, but the Prussian authorities, determined to continue the war, sent troops to march to Paris. From then on, the war waged by Prussia had turned into a war of aggression.

Here we have to mention the Paris Commune, which was invigorated by Engels as far away as China, and on March 18, the popular uprising of Paris was successful, and the Paris Commune (1871) was proclaimed (see the Paris Commune uprising), which existed until May 28, when it was brutally suppressed.

After the Franco-Prussian War, France signed a humiliating peace treaty with Prussia, and France paid an indemnity of 5 billion francs (although France quickly paid off the reparations with its strong financial and banking industry, which Bismarck did not expect), plus war losses, the total financial loss amounted to 20 billion francs, resulting in insufficient capital investment in economic development; and ceded Alsace and Lorraine, which were rich in iron ore, so that the resources needed for economic development were seriously lacking; In addition, before the reparations were paid, Germany occupied the six northern departments of France, further narrowing the domestic market. All these greatly slowed down the development of the French economy and slowed down the progress of the second industrial revolution in France.

And with the victory in the Franco-Prussian War, Germany really embarked on the road to unification. In November 1870, Bismarck, representing the North German Confederation, concluded a united peace treaty with the governments of the four southern German states, which merged with the North German Confederation to form the "German Reich". On January 18, 1871, King Wilhelm I of Prussia was officially enthroned as Emperor of the German Empire at the Palace of Versailles, France, and the unification of Germany was finally completed