Wilhelm I in the context of Frederick William IV

The Franco-Prussian War or Franco-German War, often referred to in France as the War of 1870, was a conflict between the Second French Empire and the North German Confederation led by the Kingdom of Prussia. Lasting from 19 July 1870 to 28 January 1871, the conflict was caused primarily by France's determination to reassert its dominant position in continental Europe, which appeared in question following the decisive Prussian victory over Austria in 1866.

After a prince of the Roman Catholic branch Hohenzollern-Sigmaringen had been offered the vacant Spanish throne in 1870 and had withdrawn his acceptance, the French ambassador approached Prussian King Wilhelm I at his vacationing site in Ems demanding Prussia renounce any future claims, which Wilhelm rejected. The internal Ems dispatch reported this to Berlin on July 13; Prussian chancellor Otto von Bismarck quickly then made it public with altered wording. Thus the French newspapers for July 14, the French national holiday contained translations of Bismarck's press release, but not a report from their own ambassador. A crowd in the streets of Paris demanded war, and soon French mobilization was ordered.

The Ems dispatch (French: Dépêche d'Ems, German: Emser Depesche), sometimes called the Ems telegram, was published on 13 July 1870; it incited the Second French Empire to declare war on the Kingdom of Prussia on 19 July 1870, starting the Franco-Prussian War. The actual dispatch was an internal telegram sent by Heinrich Abeken from Prussian King Wilhelm I's vacationing site at Ems to Otto von Bismarck in Berlin, describing demands made by the French ambassador concerning the Spanish succession. Bismarck, the chancellor of the North German Confederation, released a statement to the press, stirring up emotions in both France and Germany.

The name referred to Bad Ems, a resort spa east of Koblenz on the Lahn river, then in Hesse-Nassau, a new possession of Prussia.

Frederick III (Friedrich Wilhelm Nikolaus Karl; 18 October 1831 – 15 June 1888), or Friedrich III, was German Emperor and King of Prussia for 99 days from 9 March 1888 until his death in June that year, during the Year of the Three Emperors.

Known informally as "Fritz", he was the only son of Emperor Wilhelm I and was raised in his family's tradition of military service. Following the unification of Germany in 1871 his father, then King of Prussia, became German Emperor. Upon Wilhelm's death at the age of ninety on 9 March 1888, the thrones passed to Frederick, who had been German Crown Prince for seventeen years and Crown Prince of Prussia for twenty-seven years. Frederick was suffering from cancer of the larynx when he died at the age of 56, following unsuccessful medical treatments for his condition.

Kaiser-Wilhelmsland ("Emperor William's Land") formed part of German New Guinea (German: Deutsch-Neuguinea), the South Pacific protectorate of the German Empire. Named in honour of Wilhelm I, who reigned as German Emperor (Kaiser) from 1871 to 1888, it included the northern part of present-day Papua New Guinea. From 1884 until 1920 the territory was a protectorate (German: Schutzgebiet) of the German Empire. Kaiser-Wilhelmsland, the Bismarck Archipelago (including New Mecklenburg and New Pomerania), the northern Solomon Islands, the Caroline Islands, Palau, Nauru, the Northern Mariana Islands, and the Marshall Islands comprised German New Guinea.

Most of the German settlers in Kaiser-Wilhelmsland worked as plantation owners, miners, or government functionaries; the number of European settlers, including non-Germans, was never very high. In 1885, Lutheran and Catholic congregations sent clergy to establish missions; they experienced moderate, but very slow, success with the indigenous peoples. Missionaries and plantation owners alike were limited by tropical diseases and by travel and communication barriers.