On 5 July, disgruntled soldiers of the Force Publique, unhappy with their lack of advancement relative to civilian politicians, began a nationwide mutiny against their white officers.

[5] Katanga contained the vast majority of the Congo's valuable mineral resources and had attracted significant mining activity under Belgian rule.

[6] Many Katangese thought that they were entitled to the revenue generated through the lucrative industry, and feared that under the new central government led by Prime Minister Patrice Lumumba it would be redistributed among the Congo's poorer provinces.

[9] On 12 July Lumumba and President Joseph Kasa-Vubu appealed to the United Nations (UN), requesting that international troops be dispatched to the Congo to replace the Belgian forces and reestablish order.

[10] The UN Security Council complied, passing several resolutions calling for the withdrawal of Belgian troops and establishing a large multinational peacekeeping mission, the United Nations Operation in the Congo (known by its French acronym, ONUC).

Frustrated, Lumumba appealed to Eastern Bloc nations for military assistance, resulting in a conflict with Kasa-Vubu and ultimately his removal from power in September and eventual murder in January 1961.

[15] The announcement of Lumumba's death created a sense of urgency among the international community and motivated members of the UN Security Council to strengthen ONUC's powers.

[17] ONUC was not also authorised to impose a political solution by force or directly intervene in internal Congolese affairs and, as such, was primarily concerned with reducing the influence of foreign interests in the Katangese conflict.

Believing that Tshombe and his subordinates were only stalling through negotiations, UN officials decided to dispatch a new representative to Élisabethville, the Katangese capital, with demands for immediate compliance with the resolution.

Pressure from Belgium and the UN facilitated the repatriation of two officers in early June, though by the end of the month the Katangese government appeared unwilling to allow further departures.

[23] In a meeting on 12 July, Spaak suggested to Hammarskjöld that the UN should identify all the advisers it wanted to leave, so as to ease the anxieties of other Belgians' who feared their own sudden expulsion and therefore prevent another incident.

By August external involvement in Katanga had been reduced by the UN, but the "immediate" withdrawal of mercenaries and foreign advisers as called for in the February resolution had not been achieved.

[28] After long consideration of the situation, the UN Secretariat determined that if Tshombe failed to comply with its requests that foreign officers of the Katangese Gendarmerie should be forcibly arrested and deported.

The Secretariat never issued an explanation of its decision to carry out this plan, though the mercenary actions in northern Katanga proved that foreign personnel were waging civil war and months of negotiations had done little to bring about their removal.

[31] "UN Forces in the Élisabethville area will implement the Security Council Resolution of 21st Feb. 1961 by taking into custody and expelling white officers and mercenaries of the Gendarmerie."

[32] On 27 August O'Brien met with Mahmoud Khiary, Vladimir Fabry, and Raja at Kamina Base to make final preparations for the operation.

[33] Raja and his staff had already drawn up plans for the arrest of the foreign personnel[34] which had been reviewed by General Indar Jit Rikhye and diplomat Ralph Bunche and sanctioned by Hammarskjöld.

[28] At O'Brien's suggestion the plan was modified to include the occupation of the post office (which hosted the telephone exchange) and radio station and the establishment of a cordon around Katangese Minister of Interior Godefroid Munongo's residence.

[38] At the former, a temporary manager broadcast an apology for the momentary suspension of telephone services and read the central government ordinance expelling foreign mercenaries and a speech by Adoula appealing for national unity.

[41] At 05:00 in Élisabethville O'Brien dispatched a Swedish lieutenant to Tshombe's Presidential Palace and to Munongo's villa with two notes explaining the purpose of the operation.

[46] Hammarskjöld sent a congratulatory telegram to O'Brien from UN Headquarters in New York City, writing, "Congo Club[c] in congress assembled passed unanimous vote of congratulations gratification and sincere respect for an exceedingly sensitive operation carried through with skill and courage".

[48] Rikhye also expressed his disappointment, noting that "The UN had it within its grasp to close the ring and remove all unwanted individuals with perhaps a few remaining who could have hidden or vanished among the European civilians.

"[28] The day following Rum Punch Prime Minister of the Federation of Rhodesia and Nyasaland Sir Roy Welensky condemned the operation, declaring that it had "exceeded the UN's mandate.

[56] O'Brien and ONUC Chief Sture Linner made plans to continue the roundup of foreign military officials in Katanga's employ.