Diterikhs was said to be "a deeply religious man, the walls of whose private railway coach were plastered with icons" and believed that he "was waging a holy war against the Bolshevik heathens."
Diterikhs was born to a father of far German ancestry (from Bohemia), who served as a general of the Russian Imperial Army in the Caucasus, and a Russian noblewoman. In 1900, Diterikhs graduated from the Page Corps and was assigned a post in the Life Guards 2nd Artillery Brigade. In 1900, he graduated from the Nikolaevsky Military Academy in St. Petersburg. From 1900 to 1903 he served in various staff positions in the Moscow Military District. In 1903 he was appointed commander of the squadron in the 3rd Dragoon Regiment.
With the start of the Russo-Japanese War in 1904, Diterikhs became chief officer for special duties at the 17th Army Corps headquarters. He arrived at the front in Manchuria in August 1904, and participated in the Battles of Liaoyang, Shaho and Mukden. By the end of the war, he was a lieutenant. After the end of the war he returned to Moscow, and in 1906 was chief officer for special duties at the 7th Army Corps headquarters. The following year, he had the same position at the Kiev Military District headquarters. He was promoted to colonel in 1909. In 1910, he served as a senior aide at the Kiev Military District headquarters. From 1913, Diterikhs was head of the Mobilization Department of the Main Directorate of the General Staff.
With the start of World War I, Diterikhs was assigned as Chief of Staff for the Russian Third Army on the Southwestern Front under the command of General Aleksei Brusilov, with whom he assisted in planning the Brusilov Offensive in August 1916. In September of the same year, he commanded a Russian expeditionary force in Thessaloniki on the Macedonian front in support of the Serbian Army.
After the February Revolution, Diterikhs was recalled to Russia. In August 1917 the Russian Provisional Government offered Diterikhs the position of Minister of War, which he refused. By November 3, 1917, Diterikhs was promoted to the chief of staff of the Russian army's headquarters, but managed to escape arrest during the Bolshevik revolution. Diterikhs escaped to Kiev, then made his way to Siberia where the Czechoslovak Legions asked him to become their chief of staff. He helped the Czech Legion to organize their first resistance in May 1918, and commanded their Irkutsk-Chita-Vladivostok armed group.
Diterikhs was ordered by Admiral Kolchak to arrest the Ufa directory but delayed his move. After a few days on November 26, 1918 he finally agreed to obey to Kolchak's order and simultaneously resigned from the Czech Legion after a period of tense relations.
From January to July 1919 Diterikhs personally supervised the Sokolov investigation of the murder of Tsar Nicholas II. He later published a book on the subject when already living abroad titled The Murder of the Royal Family and members of the House of Romanoffs in the Urals (Убийство Царской семьи и членов Дома Романовых на Урале), in which he claimed that the execution of the Romanoffs was a ritual murder.