Question: The 2nd Army Corps took part in the Battle of Tannenberg,  fought between Russia and Germany from 26–30 August 1914, during the first month of what war?

Related documents: [0]  [DOC] The Battle of Tannenberg was fought between Russia and Germany from 26–30 August 1914, during the first month of World War I. The battle resulted in the almost complete destruction of the Russian Second Army and the suicide of its commanding general, Alexander Samsonov. A series of follow-up battles (First Masurian Lakes) destroyed most of the First Army as well and kept the Russians off balance until the spring of 1915. The battle is particularly notable for fast rail movements by the Germans, enabling them to concentrate against each of the two Russian armies in turn, and also for the failure of the Russians to encode their radio messages. It brought considerable prestige to Field Marshal Paul von Hindenburg and his rising staff-officer Erich Ludendorff. [END] 
[1]  [DOC] The 2nd Army Corps (Russian: 2-й армейский корпус ) was a formation in the Imperial Russian Army that was active during World War I. It was headquartered in Grodno prior to the outbreak of the war, and took part in the Battle of Tannenberg in August 1914. [END]  
Answer: World War I
World War I