Alexander Samsonov commanded the Russian Army at the Battle of Tannenburg. This battle was a disaster for both Samsonov and the Russian Army.
Samsonov was born in 1858 and he spent his earliest years in the Russian Army as a cavalry officer. Samsonov served in the Russo-Turkish War of 1877-1878 and in 1914, was given the command of the Russian Second Army when World War One broke out in 1914. The Russian Second Army, along with the First Army, was given the task of invading East Prussia.
The attack was Samsonov's first real military challenge and it ended in disaster. He failed to co-ordinate the movements of the Second Army with those of the First Army as he had fallen out with Rennenkampf who commanded the First Army.
As a result of this personal quarrel, Samsonov found himself and his army surrounded by the German Eighth Army, commanded by Hindenburg and Ludendorff, at Tannenburg. The Second Army was all but destroyed. Out of 150,000 men, less than 10,000 escaped capture by the Germans. The Battle of Tannenburg literally saw the destruction of a complete army. Samsonov could not bring himself to report the scale of the defeat to Nicholas II and he committed suicide in the woods at Tannenburg.