Thant began serving as Acting Secretary-General from November 3, 1961, when he was unanimously appointed by the General Assembly, on the recommendation of the Security Council, to fill the unexpired term of Dag Hammarskjöld. He was then unanimously appointed Secretary-General by the General Assembly on November 30, 1962 for a term of office ending on November 3, 1966. During this first term he was widely credited for his role in defusing the Cuban Missile Crisis and for ending the civil war in the Congo.