Thadeus Ferdinand Ludwig von Sivers (Russian: ?????´? ????´?????? ??´????, tr.
Faddey Vasil'evich Sivers; 16 October [O.S.
4] 1853 – ?), always falsely referred to as Thadeus von Sievers, was a Baltic German general who served in the Imperial Russian Army.
Sievers was most notable for his role in the Invasion of East Prussia during the initial stage of World War I, in which he commanded the 10th Army against the Germans and succeeded in taking the East Prussian Cities of Stallupönen (now Nesterov, Russia) and Goldap (now Poland) in October 1914.
Further major successes for the Russian Army in East Prussia failed to materialize.
In the Second Battle of the Masurian Lakes in February 1915, the 10th Army commanded by Sivers, was largely destroyed.
After the defeat, Sivers was ousted as Commander of the Army, even though he had been among those who had warned beforehand of the unfavorable strategic situation that had arisen.
On April 25, 1915, Sievers was sent into retirement, fell into depression, and committed suicide some time later.