1st Army (Russian Empire)
It was commanded by General Paul Rennenkampf when Russia invaded East Prussia at the outbreak of war in 1914. They were accompanied by the Second Army commanded by General Alexander Samsonov. The plan was to trap the German army in a Pincer movement between the two armies. On 17 August the First Army engaged the Germans at Stallupönen. They fought the Germans again on 20 August at Gumbinnen and defeated them. Rennenkampf thought the Germans could be finished off by Samsonov's Second Army and did not move quickly enough to help them. In late August 1914 the German and Russian second army met at Tannenberg. The Second Army was encircled and suffered complete destruction.
Let by General Paul von Hindenburg the Germans turned north to attack the Russian First army at First Battle of the Masurian Lakes in September 1914. The Russians fought hard but were driven back to the Russian border. Rennenkampf kept his troops in good order as they retreated. They set up defensive lines on the Russian border.
After another defeat near Silesia on November 11, Rennenkampf was dismissed. He was replaced by General Litvinov. The First Army again fought at Thorn and Lódź but there was no clear cut winner.
- R G Grant; et al., World War I: The Definitive Visual History (New York: DK Publishing, 2014), p. 64
- Encyclopedia Of World War I: A Political, Social, And Military History. eds. Spencer C. Tucker; Priscilla Mary Roberts (Oxford: Abc-clio, 2005), p. 979
- World War One: Student Encyclopedia, eds. Spencer Tucker, Priscilla Mary Roberts (Santa Barbara, CA: ABC-CLIO, 2006), p. 608
- The European Powers in the First World War: An Encyclopedia, ed. Spencer C. Tucker (New York; Oxford: Routledge, 2013), p. 228