Dag Hammarskjold (Swedish: Dag Hjalmar Agne Carl Hammarskjöld) (29 July 1905 – 18 September 1961) was a Swedish diplomat and the second Secretary-General of the United Nations. He served as Secretary-General from April 1953 until his death in a plane crash in what is now Zambia, on 18 September 1961. He was awarded the Nobel Peace Prize after his death in 1961.