The South American Mission Society was founded at Brighton in 1844 as the Patagonian Mission. Captain Allen Gardiner, R.N., was the first secretary. The name "Patagonian Mission" was retained for twenty years, when the new title was adopted. The name of the organisation was changed after the death of Captain Gardiner, who died of starvation in 1851 on Picton Island in South America, waiting for a supply ship from England. Gardiner thought that the original mission should be expanded from southern South America (Patagonia) to all of South America.
The Society's purpose is to recruit, send, and support Christian missionaries in South America. There were nationally based SAMS organisations in Britain, Ireland, Canada, Australia, New Zealand and the United States but during the 1990s those in Australia and New Zealand were merged with the Church Missionary Society in those countries. In 2009 the 'mother' society in Britain was also merged with CMS. SAMS was one of the early members of Faith2Share the international network of mission agencies, and the SAMS organisations in Ireland, Canada and the USA continue to play an active role within that network.
Commencing in 1838, Captain Allen Gardiner made several attempts to bring Protestant Christianity to the native peoples of South America. Returning to England in 1843 he sought support for his efforts; no British church or missionary society offered to help, so he founded his own South American Mission. His first effort to set up a mission at Gregory Bay in the Straits of Magellan in 1845 was repulsed by the natives. He worked in Bolivia in 1845–1847, but that mission effort was suppressed by the Roman Catholic clergy.
Gardiner organized another effort through the Society. With four sailors and a carpenter, he left Cardiff on the Clymene on 7 January 1848. They landed at Picton Island in Tierra del Fuego on 23 March. After being comprehensively robbed by the natives, Gardiner’s party re-boarded the ship. It sailed for Valparaiso on 1 April and they eventually returned to England.