Vsevolod Starosselsky was born into the family of Russian general Dmitry Staroselsky and Georgian princess Ekaterina Guramishvili (Guramova). He was raised in the liberal aristocratic milieu in Tiflis and trained at the Page Corps. He fought in the Savage Division during World War I, being put in command of the Kabarda Cavalry Regiment and promoted to the rank of colonel in 1916. After the Russian Revolution of 1917, he entered the service of Qajar Iran. In 1918, he became commander of the Persian Cossack Brigade, the only organized military unit in Iran, as a result of an internal coup within the brigade against its commander, Colonel Georgy Klerzhe, a suspected Bolshevik sympathizer. In this enterprise, Starosselsky was helped by the Iranian officer Reza Shah, the future shah of Iran, and tacitly supported by the United Kingdom. As historian Stephanie Cronin states, Staroselsky's primary objective in seizing command of and consolidating the Brigade after the chaos of 1917 was to preserve an instrument of Imperial Russian power in Iran while awaiting the victory of the Whites in the civil war. He exerted significance influence on the politics of Iran as he fought a military campaign against the Jangalis and their Bolshevik allies in Gilan, acceding to a dictatorial power in northern Iran. Around the same time, his relations with the British became increasingly soured and Starosselsky sought to eliminate the British influence in Tehran.