In August 1914, with France under attack on the Western Front, Russia agreed to engage Germany on the Eastern Front by invading the German territory of East Prussia. Prior to the battle, the Russian First Army, led by Paul von Rennenkampf, had defeated eight divisions of the German army. Upon taking charge of the German Eighth Army, General von Hindenburg instructed Erich Ludendorff to launch an attack on the Russian Second Army, led by Alexander Samsonov. Having tapped a Russian message, Ludendorff centered all his might on the Russian Second Army. The attack commenced on August 26, 1914, and saw the Russians retreat to Neidenburg. The German troops pursued and captured thousands of Russian soldiers. By August 29, 1914, Germany had won one of the most decisive victories won by the Central Powers in World War I.