The Grand Duke was born on November 6, 1856, to the family of Adjutant General Grand Duke Nikolai Nikolayevich (the Senior) and Grand Duchess Aleksandra Pavlovna of Oldenburg. In 1870, Nikolai Nikolaevich (the Younger) began his studies at the Nikolaev Engineering School. From 1873–1876, the Grand Duke studied at the Nicholas General Staff Academy. During the Russo-Turkish War of 1877–1878, he became an officer for special assignments under his father. In 1885, he was promoted to major general.
From 1895 to 1905, he served as inspector general of the cavalry. In 1907, the Grand Duke married Anastasia Nikolaevna (Stana), the daughter of the Montenegrin knyaz Nikolai Negosh. Stana almost immediately began to play a prominent role in the aristocratic life of St. Petersburg. With the outbreak of the First World War, the Grand Duke was appointed commander-in-chief of the Russian troops. On August 23, 1915, Emperor Nicholas II took over as commander in chief. Grand Duke Nikolai Nikolaevich the Younger was appointed viceroy in the Caucasus and commander-in-chief of the Caucasian Front.¹
At the start of 1917, Nikolai Nikolayevich did not support the revolution. He decided to leave his military activities and, in 1918, left for the Dulber Palace on the Crimea, which belonged to his younger brother Pyotr Nikolaevich. At the end of March 1919, Grand Duke Nikolai Nikolaevich the Younger and his family left Russia on the English battleship HMS Marlborough.