The Dag Hammarskjöld Medal is presented by the United Nations to the families of those who gave their lives in the service of the United Nations.
The medal was created by the Secretary-General of the United Nations Kofi A. Annan on 22 July 1997 to mark the 50th anniversary of peacekeeping operations and was named after Secretary-General Dag Hammarsjöld who died in the service of the United Nations when the plane in which he was travelling crashed on 18 September 1961 while visiting the UN mission in the Congo.
See: https://en.wikipedia.org/wiki/Dag_Hammarskj%C3%B6ld_Medal