Dag Hammarskjöld was appointed as the second Secretary-General of the United Nations in 1953 and played a pivotal role in the formation of U.N. peacekeeping forces. In the early 1960s, the Democratic Republic of the Congo faced turmoil following its independence from Belgium. The secession of the Katanga province, under the leadership of Moise Tshombe, led to ethnic tensions and conflict as many sought to control valuable resources in the region. Hammarskjöld was a strong advocate for maintaining peace and stability in Congo and sought a diplomatic resolution to the crisis. His intent to broker peace in Katanga was a significant part of his vision for international cooperation and conflict resolution.

On September 18, 1961, Hammarskjöld boarded a Lockheed L-188 Electra aircraft, intending to meet with Tshombe in Ndola, Zambia. Tragically, the flight encountered difficulties and crashed just before landing, killing all 16 people aboard. The circumstances surrounding the crash remain controversial, with various theories suggesting mechanical failure or foul play. In the aftermath, investigations were launched, yet the true cause of the crash has never been conclusively determined, leading to ongoing speculation and conspiracy theories regarding the incident.

Hammarskjöld's death marked a turning point for the U.N. and its peacekeeping missions. The challenges he faced in Congo highlighted the complexities of post-colonial governance and the international community's role in conflict resolution. His vision of an effective U.N. was thus tempered by the realities of geopolitical interests and the limitations of international diplomacy.