United Nations Operation in the Congo

The United Nations Operation in the Congo (French: Opération des Nations Unies au Congo, abbreviated to ONUC) was a United Nations peacekeeping force deployed in the Republic of the Congo in 1960 in response to Congo Crisis. ONUC was the UN's first peacekeeping mission with significant military capabilities, and remains one of the largest UN operations in both scale and operational scope.[1]

Swedish ONUC peacekeeper in the Congo

Following its independence from Belgium on 30 June 1960, the Congo descended into chaos and disorder, prompting its former colonial power to invade under the pretext of restoring law and order and protecting Belgian nationals.[2] On 12 July 1960, the Congolese Government appealed to the UN for assistance, and two days later the United Nations Security Council established ONUC to ensure the withdrawal of Belgian colonial forces and provide internal stability.[3] The first UN troops, drawn mostly from African and Asian states, reached Congo on 15 July 1960.[4]

In the face of worsening conditions—including an insurrection in Katanga, the assassination of Prime Minister Patrice Lumumba, the collapse of the central government, and the intervention of foreign mercenaries—ONUC's initial mandate gradually expanded to include protecting the territorial integrity and political independence of the Congo, preventing an impending civil war, and securing the removal of all unauthorized foreign armed forces.[5][6][7]

At its peak, UN forces numbered nearly 20,000 military personnel from over two dozen countries, led largely by India, Ireland, and Sweden.[8] During the peak of hostilities between September 1961 and December 1962, ONUC transitioned from a peacekeeping to a military force, engaging in several clashes and offensives against secessionist and mercenary forces. Following the reintegration of Katanga in February 1963, ONUC was gradually phased out, and civilian aid increased, becoming the single largest assistance effort by the UN up to that time.[2] UN personnel were withdrawn entirely on 30 June 1964.