The campaign was largely successful, but the fighting led to atrocities and gendarmes were halted by forces of the United Nations Operation in the Congo (ONUC) during the Battle of Kabalo in April 1961.

[8] Dag Hammarskjöld, the Secretary-General of the United Nations, and Ralph Bunche, his special representative, believed that engaging in Katanga would result in fighting, and refused to allow peacekeepers to enter the region.

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

[10] In response to Lumumba's removal, his political allies gathered in Stanleyville in the eastern Congo and declared a rival regime to the central government in Léopoldville.

Throughout the year additional forces were recruited, including Luba warriors, 2,000 Bazela from Pweto, Bayeke from Bunkeya, and several white volunteers from Kaniama.

[13][14] The army was largely organized, led, and trained by Belgians who were former Force Publique officers;[5] the first commander of the Gendarmerie was Jean-Marie Crèvecoeur, appointed on July 13.

[38] Due to the action of the ONUC garrison, Kabalo remained the only major town in northern Katanga not controlled by the Katangese Gendarmerie at the conclusion of their offensive.

[41] The state still had support from several Belgian politicians, such as René Clemens, the author of Katanga's constitution, and George Thyssens, who had drafted the Katangese declaration of independence and continued to serve as an important adviser.

[45] He began a far more aggressive policy of ending Katanga's secession than the interim Congolese government, and Belgium continued to pressure the Katangese authorities to begin negotiations.

Young suggested that "from this point onward, Katanga fought a mainly diplomatic and partly military rearguard action against what was in retrospect the inevitable end to the secession.

[38] The failure of the UN to convince the Katangese to dispel mercenaries from its forces led ONUC to begin Operation Rum Punch in late August 1961 to peacefully arrest foreign members of the Gendarmerie.

[48] The operation was conducted successfully without violence, and by its end 81 foreign personnel of the Katangese Gendarmerie had been arrested in Katanga and brought to Kamina base to await deportation.

[55] Lieutenant Colonel Roger Faulques, a Frenchman, was made chief of staff,[56] and he established a new headquarters near Kolwezi to coordinate anti-UN guerilla operations.

[53] The operation quickly turned violent after a sniper shot an ONUC soldier outside the post office while other peacekeepers were attempting to negotiate its surrender, and heavy fighting ensued there and at the radio station, in which over 20 gendarmes were killed under disputed circumstances.

[61] Hammarskjöld and other top UN officials who had not been fully aware of the intentions of their subordinates were deeply embarrassed by the violence, which troubled Western powers who had supported the UN.

[65] That month, Gendarmerie forces were estimated to number 13,000; mainly deployed in North Katanga, troops were also present in Manono, Albertville, Kongolo, Kolwezi, and Jadotville.

— United States Officer in Charge of U.N. Congo Affairs Charles S. Whitehouse[70] Throughout October and November the Gendarmerie was reinforced with additional mercenaries, munitions, and aircraft.

[79] After conversation with UN officials, Tshombe made an initial promise to end the fighting, but he subsequently ordered the Katangese Air Force to raid ONUC positions.

With the failure to enact a ceasefire, Major General Dewan Prem Chand of India convinced Thant to authorise a strong, decisive offensive to pre-emptively eliminate Katangese forces.

On the first day, UN forces killed 50 Katangese gendarmes before securing downtown Élisabethville,[a] the local Gendarmerie headquarters,[83] the radio station,[84] and Tshombe's presidential palace.

[88] In Kamina, the gendarmes had expected an attack on 30 December, but when one failed to occur they began to drink beer and fire flares at random, possibly to boost morale.

The same day Prime Minister Adoula received a letter from the chiefs of the most prominent Kantangese tribes pledging allegiance to the Congolese government and calling for Tshombe's arrest.

"[97] Tshombe soon expressed his willingness to negotiate after being briefly detained and released,[96] but warned that any advance on Kolwezi would result in the enactment of a scorched earth policy.

[98] Tshombe fled to Northern Rhodesia on a Rhodesian Air Force plane,[99] and managed to reach Kolwezi,[99] the only significant location that remained under Katangese control.

[101] Meanwhile, mercenaries in the Kolwezi area had taken Tshombe's threats about a scorched earth policy seriously and planted explosives on all nearby bridges, the Nzilo Dam (which provided most of Katanga's electricity), and most UMHK mining facilities.

Tshombe was invited to return to the Congo to assist in negotiating a political solution, and in July 1964 he was installed as Prime Minister with the hope that he could reach an agreement with the rebels and that his presence would ensure no new secession attempts in Katanga.

Political deadlock ensued as Parliament refused to approve Kasa-Vubu's new appointee to the premiership, and in November Mobutu launched a coup and assumed the presidency.

At the end of the mutinies, the gendarmes agreed to a cease-fire proposed by Organisation of African Unity Secretary General Diallo Telli under which they could gain amnesty by returning to the Congo.

However, historian Pedro Aires Oliveira notes that the gendarmes cared more about fighting the Democratic Republic of the Congo than participating in the Angolan war and as a result were closely watched by the Portuguese authorities.

[126][127] During the Angolan Civil War (from 1975 to 2002), the FLNC, composed of ex-gendarmes called the "Tigres", fought on the side of the MPLA against the National Liberation Front of Angola (FNLA).