Born on May 11th, 1789, he graduated in Arts at Aberdeen. He entered the Bengal Army as Assistant Surgeon on Nov 25th, 1824. Promoted to Superintending Surgeon on March 1st, 1843, he became a member of the Bengal Medical Board and Inspector-General of Hospitals on May 16th, 1853, Surgeon General on the following August 26th, and he retired on April 10th, 1857. For the first time officers of the IMS became eligible to receive the CB (military division), and Renny was one of four thus decorated for distinguished service as 'Superintending Surgeon Bengal'. He served in the Nepal War, with Medal, 1814-1815; the Third Maratha or Pindari War, 1817-1818; the Afghan War, 1839-1840; and the Second Sikh or Punjab War, 1848-1849, when he was present at the Battles of Ramnagar, Chilianwala, and Gujerat (*see* Dispatches, *London Gazette*, March 3rd and April 19th, 1849). He died at Exmouth on March 26th, 1856.