 Prince Roman Petrovich was born in the Peterhof Palace in St. Petersburg the only son of Grand Duke Peter Nikolaevich of Russia and his wife Princess Milica of Montenegro.Prince Roman belonged to the Nikolaevichi branch of the Russian Imperial Family which was founded by his grandfather Grand Duke Nicholas Nikolaevich.In 1916 having graduated from the Nicholas Engineering Academy of Kiev, Prince Roman was posted to serve in a Caucasian Sappers Regiment on the Turkish front.