The Reinsurance Treaty was a diplomatic agreement between Germany and Russia, signed on June 18, 1887. Initiated by German Chancellor Otto von Bismarck, this treaty aimed to address the shifting dynamics in European politics, particularly the rise of alliances that threatened Germany's security. It came in response to the Franco-Russian Alliance, which was formed earlier and posed a potential threat to Germany should a conflict arise with either France or Russia. The treaty stipulated that if either Germany or Russia were attacked by a third party, the other would remain neutral, thus providing both nations with a sense of security and stability.

Bismarck understood that maintaining a good relationship with Russia was essential to counterbalance the growing power of France. The innovative aspect of this treaty was its ability to ensure mutual respect while allowing both nations to pursue their interests independently. While initially welcomed, the agreement later faced scrutiny as power dynamics in Europe transformed. Once Bismarck left office in 1890, his successors failed to renew the treaty, leading to significant shifts in alliances that would ultimately contribute to the outbreak of World War I.

The Reinsurance Treaty exemplified the complexities of European diplomatic relations in the late 19th century, reflecting Bismarck’s realpolitik strategy of maintaining stability through pragmatic agreements. The failure to renew the treaty underscored the fragility of diplomatic relations during this period and set the stage for heightened military tensions in Europe as alliances shifted towards the impending Great War.