As part of the larger Congo Crisis (1960–64), the siege of Jadotville began on 13 September 1961, lasting for five days. While serving under the United Nations Operation in the Congo, a small contingent of the Irish Army's 35th Battalion, designated "A" Company, were besieged at the UN base near the mining town of Jadotville by Katangese forces loyal to the secessionist State of Katanga. The siege took place during the seven-day escalation of hostilities between ONUC and Katangese forces during Operation Morthor. Although the contingent of 155 Irish soldiers repelled attacks by a 3,000-strong Katangese force, they were eventually forced to surrender after running out of ammunition and water. "A" Company was subsequently held as prisoners of war for approximately one month, before being released on 15 October as part of a prisoner exchange. The Irish forces inflicted approximately 1,300 casualties on the Katangan force, with no deaths amongst "A" Company.

The State of Katanga, also known as the Republic of Katanga, was a breakaway state that proclaimed its independence from Congo-Léopoldville on 11 July 1960 under Moise Tshombe, leader of the local Confédération des associations tribales du Katanga (CONAKAT) political party. The new Katangese state did not enjoy full support throughout the province and was constantly plagued by ethnic strife in its northernmost region. It was dissolved in 1963 following an invasion by United Nations Operation in the Congo (ONUC) forces, and reintegrated with the rest of the country as Katanga Province.