His parents' marriage was unhappy and Dmitry was still a child when his father started a new family with his mistress, a Russian ballerina. A second family setback scared him even further. Dmitry was 14 when his eldest brother
Nikolai Konstantinovich was disinherited, declared insane and sent into internal Russian exile, after stealing some diamonds from an icon in his mother's bedroom. Grand Duchess Alexandra Iosifovna made her three remaining sons (
Konstantin, age 16, Dmitry, age 14, and Vyacheslav, age 12) promise her that they would never drink, never give themselves to a life of self-indulgence, and never forget that all the privileges of their wealth and rank were meant for use and not enjoyment. Brought up under these conditions, the younger Konstantinovich grand dukes grew into thoughtful, introspective men At the age of 15, Dmitry, with his younger brother Vyacheslav, was enrolled as a cadet aboard the tender
Kadetski. Together the two brothers underwent the rigors of life at sea. During their training cruises through the
Gulf of Finland, they spent their time drilling, standing watch, and taking turns leading their fellow cadets. In 1877, the 17-year-old Dmitry made his first official public appearance as a member of the Imperial family, he joined Alexander II with his father and cousins
Grand Duke Sergei and
Grand Duke Paul Alexandrovich on a journey to southern Russia in the aftermath of the
Russo-Turkish War (1877–1878). and
Konstantin with their sister
Grand Duchess Vera Dmitry soon disappointed his father's wishes when he decided to abandon his career in the Navy in favor of the Imperial Army. He used the interval of an illness to ask his father to allow him to join the army. It was a blow to Konstantin to see his third consecutive son to leave the navy, but Dmitry begged his father and with the intervention of
Alexandra Iosifovna, he was eventually allowed to leave the Navy and join the Horse Guards regiment in 1879. Like his parents, Dmitry was musical; he had a particular love for Russian church music. In later years, he often sang in the chapel choirs at Strelna, the
Marble Palace and the Pokrovsky Convent in
Kiev. Duty stood at the core of his being and he was fiercely critical of a system, which pushed members of the Imperial family forward simply because of who they were. He believed that their promotions should be earned Intensely shy, Dmitry preferred to avoid society, but on summer evenings at
Petergof he often rode from Strelna to Znamenka, the house of his cousin,
Grand Duke Pyotr where he was a welcome guest. Peter's wife,
Grand Duchess Militsa, played the piano while Dmitry was usually persuaded to join in, accompanying with his own singing of Russian folk songs. ==Military career==