The article deals with the structure and top personal nominations in the Supreme Command of Russian Armed Forces during World War I. In that period the General Headquarters (Stavka) which comprised the Commander-in-Chief, his Staff, the guards and some special units, was in charge of all the operations on land and sea. Stavka was located first (August 1914-August 1915) in special trains at Baranovichi and later (August 1915-March 1918) moved to Mogilev. Its war history can be divided into four phases. Phase One (August 1914-September 1915) when the Supreme Command was still in the hands of Grand Duke Nikolai Nikolaevich, grandson of Tsar Nikolai I, saw a modest expansion of the structures of the General Staff. Phase Two (September 1915-March 1917) opened with Tsar Nikolai II taking personal command himself. It was period of major reshuffles and innovations, chief among them the creation of a separate Field Staff of the Imperial Navy. In Phase Three, inaugurated by the February Revolution and the abdication of the Tsar (March-November 1917), Stavka found itself under the control of the Provisional Government. A peculiar feature of that period was fast rotation in the post Commander-in-Chief. Phase Four, which followed the seizure of power by the Bolshevik Party in November 1917, was marked by the occupation of the General Headquarters by troops loyal to the new regime (December 1917) and the formal disbanding of Stavka in March 1918.