Dag Hjalmar Agne Carl Hammarskjöld ( , ; 29 July 1905 – 18 September 1961 ) was a Swedish economist and diplomat who served as the second Secretary-General of the United Nations . Hammarskjöld was the youngest person to have held the post , at an age of 47 years upon his appointment . His second term was cut short when he died in the crash of his DC-6 airplane ( whose cause is still disputed ) while en route to cease-fire negotiations during the Congo Crisis . He is one of only four people to be awarded a posthumous Nobel Prize
crash of his DC-6 airplane
1961 Ndola United Nations DC-6 crash
Dag Hammarskjöld