Combat Organization of the Socialist Revolutionary Party

The Combat Organization (Russian: Боевая организация партии социалистов-революционеров, romanized: Boyevaya organizatsiya partii sotsialistov-revolyutsionerov, BO) was the terrorist wing of the Socialist Revolutionary Party (PSR) in the Russian Empire, active from 1902 to 1907. Established by the PSR Central Committee, its primary purpose was to carry out political assassinations against high-ranking government officials to destabilize the Tsarist regime and further the party's revolutionary aims.

Led by figures such as Grigory Gershuni, Boris Savinkov, and, notoriously, the Okhrana agent Yevno Azef, the Combat Organization operated with a high degree of autonomy and secrecy. Its members, often driven by a mix of revolutionary idealism and personal motivations, were responsible for some of the most sensational political assassinations of the early 20th century, including those of Interior Ministers Dmitry Sipyagin (1902) and Vyacheslav von Plehve (1904), and Grand Duke Sergei Alexandrovich (1905).

The organization's activities were significantly impacted by internal dynamics, police infiltration, and shifts in PSR party policy regarding the use of terror. The exposure of Yevno Azef as a police agent in 1908 dealt a devastating blow to the Combat Organization and the PSR, leading to a sharp decline in its activities and a crisis of confidence within the revolutionary movement. Despite attempts to revive its operations, the Combat Organization largely ceased to function effectively after Azef's exposure, though isolated acts attributed to its legacy or attempts at revival continued until around 1911.