Dag Hjalmar Agne Carl Hammarskjöld was Secretary-General of the United Nations from 10 April 1953 until 18 September 1961 when he met his death in a plane accident while on a peace mission in the Congo. He was born on 29 July 1905 in Jonkoping in south-central Sweden. The fourth son of Hjalmar Hammarskjöld, Prime Minister of Sweden during the years of World War I, and his wife Agnes, M.C. (b. Almquist), he was brought up in the university town of Uppsala where his father resided as Governor of the county of Uppland.