When the Russo-Ottoman Crimean War started he was sent out with a small flotilla to bring troops and material to Batumi. Because of stormy weather he decided to stop and wait in Sinope, where he was attacked by Russian Admiral Pavel Nakhimov on November 30 of 1853. Osman's flotilla was destroyed, he himself was wounded in the foot and taken prisoner. He was released after the Treaty of Paris (1856), and although the Patrona rank had been abolished in the meantime, he remained a member of the Admiralty.