Kilner Swettenham was born in Dublin in May 1780. His father was Kilner (or Killiner) Swettenham, Lord Mayor of Dublin; his mother was Elizabeth Toone. He was first placed in the 9th Native Infantry in August 1798 but transferred to the 2nd BNC. He was a lieutenant on 29 May 1800 and was on active service in Jumna Doab in 1803. In the Second Maharatta War of 1803-5 he fought at Delhi, Laswarri and Deig. He went on furlough from 1810-13 and then served in the Nepal War of 1814-15, promoted to captain on 22 Sep 1815. He reached the rank of Major on 1 Sep 1818, and Lt-Col on 7 Oct 1824. He transferred from the 2nd BLC and had a series of commands starting with the 6th BLC, then the 5th on 12 Feb 1825, the 1st in 1826, the 8th later that year, and the 9th on 4 Nov 1826. He was invalided on 26 Oct 1827 and on 25 Jan 1828 he was given command of the Burdwan Provincial Battalion, but he died at Burdwan on 27 Oct 1829. He was married to Sydney Maria Fletcher from Ceylon. She died in 1877, a very old lady.
