On the outbreak of the First World War General Alexander Samsonov was given command of the Russian Second Army for the invasion of East Prussia. He advanced slowly into the south western corner of the province with the intention of linking up with General Paul von Rennenkampf advancing from the north east.

The commander of the German Eighth Army, General Maximilian Prittwitz, was dismissed for ordering the retreat when faced with the Russian Second Army. General Paul von Hindenburg and General Erich Ludendorff were sent forward to meet Samsonov's advancing troops. They made contact on 22nd August, 1914, and for six days the Russians, with their superior numbers, had a few successes. However, by 29th August, Samsanov's Second Army was surrounded.

General Alexander Samsonov attempted to retreat but now in a German cordon, most of his troops were slaughtered or captured. Only 10,000 of the 150,000 Russian soldiers managed to escape. Shocked by the disastrous outcome of the battle, Samsanov committed suicide. The Germans, who lost 20,000 men in the battle, were able to take over 92,000 Russian prisoners. In Britain, all news of the Russian defeat at Tannenberg was kept from the public.