The term "Grand Dukes of Russia" refers to members of the Russian royal family who held the title of Grand Duke, a rank just below that of the Emperor. This title was often granted to the sons and brothers of the reigning monarch, allowing them to govern specific regions or territories within the Russian Empire. The Grand Dukes played significant roles in the administration and military of the empire. The most notable Grand Duke was Grand Duke Nicholas, who served as the commander of the Russian army during World War I. The title was abolished following the Russian Revolution of 1917, which led to the end of the monarchy and the establishment of the Soviet Union.