Russian grand duke and army officer who served as commander in chief against the Germans and Austro-Hungarians in the first year of World War I and was subsequently (until March 1917) Emperor Nicholas II's viceroy in the Caucasus and commander in chief against the Turks.

The son of the emperor Alexander II's brother, the grand duke Nikolay Nikolayevich “the Elder,” Nicholas was educated at the general staff college and commissioned in 1872. He served in the Russo-Turkish War of 1877–78 and as inspector general of cavalry (1895–1905), introducing major reforms in training and equipment. He was made commander of the St. Petersburg military district in 1905 and also was appointed first president of the short-lived imperial committee of national defense.

When World War I began, Emperor Nicholas II abandoned his intention to lead the Russian armies himself and appointed the grand duke Nicholas commander in chief. Despite their early successes, the Russians were outgeneralled by the German chief of staff Erich Ludendorff and eventually were immobilized by munitions shortages. The grand duke is considered to have done as well as possible with the general staff's plans he was obliged to follow.

On Sept. 5 (Aug. 23, Old Style), 1915, the emperor assumed the supreme command. He sent the grand duke to the Caucasus, where he remained until the overthrow of the monarchy in 1917. The emperor's last official act was to appoint the grand duke commander in chief once more; but his appointment was canceled almost immediately by Prince Georgy Y. Lvov, head of the provisional government. Two years later Grand Duke Nicholas sailed from Russia in a British warship. He lived in France until his death, heading an organization that sought to unite all anticommunist Russian émigrés.