The Reinsurance Treaty was a diplomatic agreement between the German Empire and the Russian Empire that was in effect from 1887 to 1890. The existence of the agreement was not known to the general public, and as such, was only known to a handful of officials in Berlin and St. Petersburg. The treaty played a critical role in German Chancellor Otto von Bismarck's network of alliances and agreements, which aimed to keep the peace in Europe as well as maintaining Germany's economic, diplomatic and political dominance. It helped calm tensions between both Russia and Germany.
The treaty provided that both parties would remain neutral if the other became involved in a war with a third great power, with the exception of if Germany attacked France or if Russia attacked Austria-Hungary. Germany made concessions to Russia by changing its stance on Bulgaria and Eastern Rumelia (now part of southern Bulgaria), agreeing that they were in the Russian sphere of influence and agreeing to support Russian action to keep the Black Sea as its own preserve. After Bismarck had lost power in 1890, his enemies in the Foreign Ministry convinced the Kaiser that the treaty was too much in Russia's favor and should not be renewed. The cancellation, as with the treaty itself, was generally held from the public. Russia, however, had not wanted to terminate the alliance. Needing new allies, Russia opened negotiations with Germany's enemy France. The resulting Franco-Russian Alliance of 1891–1892 to 1917 rapidly began to take shape. Historians consider the new alliance a major disaster for Germany and one of the long-term causes of the First World War.[1]