The Grand Duchy of Mecklenburg-Strelitz was a member state of the German Confederation from 1815 to 1866. It consisted of two detached parts, the duchy of Strelitz to the East of Mecklenburg-Schwerin, and the principality of Ratzeburg in the West. Mecklenburg-Strelitz attempted to stay neutral during the war of 1866 until Bismarck pressured the Grand Duke by threatening occupation; shortly afterward, they joined Prussia. A military convention was signed 9 November 1868 and a further convention was concluded in December 1872. A strange anomaly existed, called the Grand Ducal Military Department in Neustrelitz, which provided a quasi-War Ministry that gave the Grand Duke some sense of sovereignty. After the Prussian-Austrian War, it became a member state of the North German Confederation in 1867. Mecklenburg-Strelitz was a member state of the German Empire in 1871. The form of government was a monarchy limited by a representation of estates, and like Mecklenburg-Schwerin, there was no parliament. Mecklenburg-Strelitz continued feudal serfdom very similar to Mecklenburg-Schwerin.
Adolf, the Grand Duke, was the cousin of the Grand Duke of Mecklenburg-Schwerin, Friedrich-Franz. This 35-year-old bachelor mysteriously killed himself several months before the end of the war (Feb 1918) when his affair was discovered. He had had a long-term affair with Mafalda Salvatini, an Italian opera singer, with whom he had two illegitimate sons. The next-in-line, Duke Karl-Michael, hated Germany, lived in Russia, and served in the Army of the Tsar. So when the war ended there was no “Grand Duke;” therefore, the cousin (Fredrick Franz IV of Mecklenburg Schwerin, the regent) abdicated for both Mecklenburg Schwerin and Mecklenburg-Strelitz. Karl-Michael renounced his claim in a letter in 1914 but it did not get delivered until 1919 due to the Russian revolution. Eventually, Karl-Michael was allowed to adopt an heir and the line lives on.
Consuls were maintained for trade with Belgium, Great Britain, Italy, Japan, Austria-Hungary, Russia, Spain, Prussia, Hamburg, Brazil, Paraguay, Rumania, Italy, Mexico, France, Portugal, Switzerland, Sweden, and in Norway.