Dag Hjalmar Agne Carl Hammarskjöld was a Swedish economist and diplomat who served as the second Secretary-General of the United Nations from April 1953 until his death in a plane crash in September 1961. As of 2026, he remains the youngest person to have held the post, having been 47 years old when he was elected. He was a son of Hjalmar Hammarskjöld, who served as Prime Minister of Sweden from 1914 to 1917. The Nobel Peace Prize 1961, announced October 23, 1961. Dag Hammarskjöld, “for developing the UN into an effective and constructive international organization, capable of giving life to the principles and aims expressed in the UN Charter”. Dag Hammarskjöld: born 1905, Jönköping, Sweden. Wiki link Data: the Nobel Foundation (CC0).