Nikolay Yudenich was a nobleman, born into a family of a collegiate councilor [a civil rank in the Russian Empire]. He graduated from the 3rd Aleksander Military School (1881), the Nicholas General Staff Academy (1887). A participant of the Russo-Japanese War and World War I. Chief-of-Staff (from 1914) and Commander of the Caucasian Army (1915)  General of Infantry (1915). Under the command of Yudenich, Russian troops won a number of major victories over the forces of the Ottoman Empire.

After the February Revolution of 1917, he was appointed Commander-in-Chief of the Caucasian Front. May 1917 saw him removed from command by Minister of War Aleksander Kerensky for resisting the orders of the Provisional Government. In August 1917, Yudenich took part in the work of the State Conference in Moscow. He supported General Lavr Kornilov affair. After the October coup of 1917, Yudenich conducted underground anti-Bolshevik activity in Petrograd.

In late 1918 – early 1919, he secretly moved to Finland with his family. In January 1919, the emigrant Russian Political Committee in Helsingfors proclaimed him the leader of the White movement in the North-West of Russia. With the support of the Committee, he launched work to unite anti-Bolshevik forces in the North-West. Yudenich negotiated with the Supreme Ruler of Russia Aleksander Kolchak and the Commander-in-Chief of the Armed Forces of the South of Russia, Anthon Denikin, as well as the representatives of Great Britain, France, the USA, the governments of Sweden, Estonia, Latvia, Finland.

In May 1919, he headed the Political Conference set up in Helsingfors to help the Northwestern Army advancing on Petrograd from the territory of Estonia. In June, Kolchak appointed Yudenich Commander-in-Chief of all land and naval armed forces in the Northwestern Front. After the defeat of Carl Gustaf Mannerheim in the presidential election in Finland (June 1918), which implied the collapse of the Whites’ hopes to obtain active help from the Finns, Yudenich moved to Estonia.

Since August 1919, he held the post of Minister of War of the newly established Northwestern Government. In autumn, he organized a second offensive against Petrograd, during which Yamburg, Luga, Krasnoe Selo, Gatchina, and Detskoe Selo were captured. Due to the lack of reserves and the lengthy front of the Northwestern Army the units of the Workers’ and Peasants’ Red Army under the personal leadership of the Chairman of the Revolutionary Military Council of the Republic, Leon Trotsky, were enabled to stop and defeat the enemy during the counteroffensive. By the end of November, Yudenich’s troops crossed the Estonian border, in Estonia, they were disarmed and interned by the former allies.

In January 1920, Yudenich declared the dissolution of the Northwestern Army. He was arrested by the detachment of Stanislav Bulak-Balakhovich facilitated by the Estonian authorities. He was released thanks to the intercession of the French and British missions. In February 1920, he left for London. In emigration, he withdrew from political activity and lived his last years in France.