Paul von Rennenkampf (1854-1918) was a Russian military leader during World War I.
He joined the Russian Army at 19 and attended the Nikolaevsky Military Academy in St. Petersburg six years later. After graduating in 1882, he was appointed to the General Staff and reached the rank of major-general by 1900.
Rennenkampf commanded a cavalry unit during the Boxer Rebellion (1900), and was responsible for the capture of Tsitsihar and Kirin. He also participated in the Russo-Japanese War (1904-05), but was criticised for his campaign in north-eastern Korea. After the Battle of Mukden in 1905, General Alexander Samsonov accused Rennenkampf of failing to assist him during the fighting and the two men came to blows.
After the Russo-Japanese War Rennenkampf restored part of his reputation dealing with revolutionaries in Siberia. Afterwards he was appointed Chief-of-Staff of the Vilno Military District.
At the start of World War I, Rennenkampf was given command of the Russian First Army for the invasion of East Prussia, advancing from the North East. His behaviour during the Battle of Tannenberg, particularly his failure to coordinate with Samsonov, resulted in some members of the military high command trying to have him removed from office.
After relative success at the Battle of Gumbinnen in mid-August, failure at the First Battle of the Masurian Lakes that same month and at the Battle of Lodz in November 1914 led to Rennenkampf's dismissal amid recriminations of incompetence. Rennenkampf then retired to the Black Sea coast. Rennenkampf was later killed after refusing to join the Bolshevik forces during the Russian Civil War.