The United Nations Operation in the Congo 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.
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. 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. The first UN troops, drawn mostly from African and Asian states, reached Congo on 15 July 1960.