Pennington was in Florence Nightingale's Scutari Hospital during April to May 1855 and became the Camp Cook at Scutari in July 1855. Pennington was invalided back to Great Britain in June 1856 and purchased his discharge from the Army in September the same year having served 2 years and 240 days. Pennington took part in the Battles of the Alma, Balaclava and the Siege of Sebastopol.