When the king of Denmark died in late 1863, a controversy over Schleswig-Holstein gave Bismarck further opportunities. In brief, the duchies of Schleswig and Holstein at the southern base of the Danish peninsula had been ruled by the king of Denmark, but not as part of Denmark.
A fifteenth-century guarantee assured the duchies that they could never be separated from one another. Yet Holstein to the south was a member of the German Confederation; Schleswig to the north was not. Holstein was mostly German in population; Schleswig was mixed German and Danish.
In 1852 Prussia joined the other powers in the Protocol of London, agreeing on an heir who would succeed both to the Danish throne and to the duchies, and recommending that Denmark and the duchies be united by a constitution. But when the constitutional union of Denmark and the duchies was attempted, the duchies resisted, and the Danes tried to incorporate Schleswig alone.
German patriots there and elsewhere objected. The Prussians and Austrians wanted the duchies to have special representation in the Danish parliament and insisted that Schleswig not be incorporated into Denmark; nonetheless, the king of Denmark had supported annexation.
In 1863 Bismarck moved to win the duchies for Prussia. First, he maneuvered Prussia and Austria together into a victorious war against Denmark (1864). Then he quarreled with the Austrians over the administration of the duchies. At the Convention of Gastein in 1865 it was decided that Prussia was to administer Schleswig and that Austria was to administer Holstein.
Bismarck next tried to tempt France into an alliance. He failed, but he did succeed in signing a secret treaty with the Italians, who obliged themselves to go to war on the side of Prussia if Prussia fought Austria within three months, the stake being Venetia. This was contrary to the constitution of the German Confederation, which forbade members to ally themselves with a foreign power against other members. Finally, Bismarck suddenly proposed that the German Confederation be reformed, and that an all-German parliament be elected by universal suffrage, which everybody knew he actually opposed.
Bismarck probably advanced this proposal to make it appear that his quarrel with Austria involved more than the Schleswig-Holstein question. Yet the proposal may also have reflected his calculation that enfranchisement of all Germans would weaken the Progressive party and would produce many conservative and royalist votes from the peasantry. Historians continue to debate Bismarck’s actual intentions, many of them contending that it is from his rise to power that the German states departed from the broad western European movement toward parliamentary democracy.
Austria now laid the Schleswig-Holstein question before the Diet of the Confederation. Bismarck ordered Prussian troops into Holstein and declared that Austrian motions in the Diet were unconstitutional, provoking war with Austria. The result was a German civil war, since Bavaria, Wurttemberg, Saxony, Hanover (the other four German kingdoms), and most of the lesser German states sided with Austria.
The war lasted only seven weeks and was decided in three. The Austrians, fighting on two fronts, had to commit a substantial part of their forces against Italy. Skillfully using their railway network, the telegraph, and their superior armaments, the Prussians quickly overran the northern German states, invaded Bohemia and defeated the Austrians at Sadowa, defeated the Bavarians, and entered Frankfurt, seat of the German Confederation.
Hanover, Hesse-Cassel, and Nassau were annexed to Prussia and their dynasties expelled, and Schleswig and the free city of Frankfurt were taken over by terms of the Peace of Prague in August. Except for the cession of Venetia to Italy in the Peace of Vienna in October, Austria suffered no territorial losses but did pay a small indemnity. Most important from Bismarck’s point of view, Austria had to withdraw forever from the German Confederation, which now ceased to exist.
An assembly elected by universal manhood suffrage now adopted a constitution for the new North German Confederation, of which the Prussian king was president. The future parliament (Reichstag) was to have no power over the budget, and the ministers were not to be responsible to it. Instead, a Federal Council (Bundesrat) of delegates from the member states, who voted according to instructions from their sovereigns, would reach all key policy decisions in secret and would have veto power over any enactment of the Reichstag. A chancellor would preside over the Bundesrat, but would not have to defend its decisions before the Reichstag. Since Prussia now had not only its own votes in the Bundesrat but also those of the newly annexed states, Bismarck’s plan in effect made it possible for the king of Prussia to run Germany.
As long as Bismarck needed the benevolent neutrality of Napoleon III, he had hinted that he might not object if Napoleon took Belgium. Now the gullible Napoleon found that Bismarck no longer remembered the matter. Hoping to be compensated for his assistance in making peace between Prussia and Austria, Napoleon III tried to acquire Luxembourg by purchase from the king of Holland.
Again he was frustrated by Bismarck. Napoleon III tried to obtain an alliance with Austria and Italy to thwart further Prussian expansion, but the Austrians shied away from a commitment, and the Italians were unable to reach an agreement with the French because of the Roman question.
The Spaniards ousted their queen in 1868, and one of the candidates for the throne was a Hohenzollern prince, whom Bismarck secretly backed by discreetly bribing influential Spaniards. Because of family dynastic practice, it was necessary to secure the consent of King William I of Prussia, a consent Bismarck finally extracted without hinting that war with France might result. Napoleon III, also deep in Spanish intrigue, feared that a Hohenzollern on the Spanish throne would expose France to a two-front attack. French diplomatic pressure was exerted directly on King William, and the Hohenzollern candidate withdrew. At this moment, Bismarck seemed to be defeated.
But the French, made overconfident by their success, now demanded that William publicly endorse the withdrawal of the Hohenzollern candidacy and promise never to allow it to be renewed. William, who was at Ems, courteously refused and sent a telegram to Bismarck describing his interchange with the French ambassador.
Bismarck then abridged the Ems telegram and released his doctored version to the press and all the European chanceries. He made it seem that the ambassador had provoked William, who in turn had snubbed the ambassador. Public opinion in Germany was now inflamed, and Bismarck set out to bait the French still further by encouraging a violent campaign against them in the German press. The French, led by a war parry eager to stop German expansion, reacted as Bismarck had hoped; they declared war on July 19, 1870.
Within six weeks the Germans had advanced into France, bottled up one French army inside the fortress of Metz, defeated another at Sedan, and captured Napoleon III himself. The protracted siege of Paris followed, ending in surrender early in 1871. A new French government had to sign the treaty of Frankfurt. Bismarck forced the French to pay a massive indemnity, to cede Alsace and much of Lorraine, and to support German occupying forces until the indemnity had been paid.