On 7 April 1953 , Chairman of the Swedish delegation to the General Assembly Dag Hammarskjöld was appointed Secretary-General of the United Nations , succeeding the first Secretary-General , Trygve Lie . Hammarskjöld was sworn in on 10 April and he was unanimously reelected for a second term on 26 September 1957 . On 18 September 1961 , while en route to negotiate a cease fire between UN forces and Moise Tshombe 's Katangese troops in Congo , Hammarskjöld 's Douglas DC-6 airliner crashed with no survivors in Northern Rhodesia . The death of the Secretary-General sparked a succession crisis within the UN , as there was no line of succession in place and the Security Council had to vote on a successor
crashed with no survivors
1961 Ndola United Nations DC-6 crash
Sweden and the United Nations