After the outbreak of the February Revolution of 1917, Ossendowski moved yet again, to Siberia, this time to Omsk, where he started giving lectures at the local university. After the October Revolution and the outbreak of the Russian Civil War, he also got involved in the counterrevolutionary Russian government led by Supreme Governor Admiral Aleksandr Kolchak. He served at various posts, among others as an intelligence officer, an envoy to the intervention corps from the United States and an assistant to the Polish 5th Rifle Division of Maj. Walerian Czuma. In 1918 he was responsible for the transfer of many tsarist and White Russian documents to the Entente, including proofs (many apparently forged) of German support (confirmed later from German archives) for Lenin and his Bolsheviks (so-called Sisson Documents).