The Reinsurance Treaty (June 18 1887) was an attempt by Bismarck to continue to ally with Russia after the League of the Three Emperors broke down.

Bismarck felt that this was essential to continue the diplomatic isolation of France so ensuring German security.

The secret treaty was split in two parts:

1. Russia pleged to remain neutral in the case of a french attack on Germany, Germany pleged to remain neutral in the case of an austrian attack on Russia.
2. In the most secret completion protocol Germany declared herself neutral in the case of a Russian intervention in the Bosporus and the Dardanelles.

As part of Bismarcks system of periphere diversion the treaty was highly depending on his person. After the dismissal of Bismarck, the German Office of foreign affairs felt unable to obtain success in keeping this policy. In fact was Bismarcks plan to make Russia dependend on German friendship in the question of the Bosporus, only working, if Russia abstained from a russo-french alliance. The Reinsurance Treaty did not exclude that! Further more, it didn't protect Germany from a french attack, but gave Russia the right, under reference to his historical rights on the Balkans, to attack Austria-Hungary.

When in 1890 Russia asked for a renewal, Germany refused persistently. The reason for the German decision was that the treaty was thought to undermine Germanys credibility with his Allies of the Triple Alliance (1882) with Austria-Hungary and Italy.

In 1896 the treaty was exposed by a German newspaper, the Hamburger Abendnachrichten, which forced an uproar in Germany and Austria-Hungary.