Operation Grandslam was an offensive undertaken by United Nations peacekeeping forces from 28 December 1962 to 15 January 1963 against the forces of the State of Katanga, a secessionist state rebelling against the Republic of the Congo (now the Democratic Republic of the Congo) in Central Africa. The conflict ended with the defeat of the State of Katanga and its subsequent dissolution.
The United Nations had tried several times to reconcile the government of the Congo with the State of Katanga, which had declared independence under Moïse Tshombe with Belgian support in 1960. Though initially limiting its actions, the United Nations Operation in the Congo became increasingly impatient towards Katanga and Tshombe, drawing up plans to resolve the situation through force. Tshombe continuously violated agreements he had made with the United Nations and the Congolese government by building up his forces and bringing foreign mercenaries into the conflict. The situation reached a breaking point in December 1962 when Katangese gendarmes attacked peacekeeping forces in Katanga. United Nations Secretary-General U Thant authorised a retaliatory offensive to eliminate secessionist opposition.
Reinforced by aircraft from Sweden, United Nations peacekeepers completed the first phase of the operation, securing the Katangese capital, Élisabethville and destroying much of the Katangese Air Force by the end of the year. In early January, the United Nations forces turned their attention towards remaining strongholds in southern Katanga. Indian peacekeepers exceeded their orders and crossed the Lufira River ahead of schedule, generating panic behind the Katangese lines and embarrassing the United Nations leadership. Tshombe, realising that his position was untenable, approached Thant for peace. On 17 January 1963, he signed an instrument of surrender and declared the Katangese secession to be over. The central government reorganised the provincial administration of Katanga to weaken its political structure. Tshombe initially participated but feared his arrest and fled to Europe.
Many Katangese gendarmes and their mercenary leaders took refuge in Angola to reorganise, acting under orders from Tshombe. In 1964, Tshombe was welcomed back to the Congo and made prime minister. He immediately called on his forces to suppress communist revolts in the east and centre of the country. This they accomplished but Tshombe was dismissed from his post in 1965, ultimately losing all contact with them following his imprisonment in Algeria in 1967. Relations between the new central government and the gendarmes soured and, after a mutiny was repressed, they returned to Angola. An insurgency for Katangese secession continues to the present day.
Background
Katanga's secession
Following the Republic of the Congo's independence from Belgium in 1960, the country fell into disorder as the army mutinied. Shortly thereafter South Kasai and the State of Katanga declared independence from the Congolese government. The latter contained the vast majority of the Congo's valuable mineral resources and attracted significant mining activity under Belgian rule. Many Katangese thought that they were entitled to the revenue generated through the lucrative industry, and feared that under the new central government it would be distributed among the Congo's poorer provinces. Resulting nativist politics with support from the Belgian government and private interests such as the Union Minière du Haut Katanga (UMHK) precipitated the Katangese secession.
The deposition—and eventual murder—of Prime Minister Patrice Lumumba caused further issues in the country, leading to the declaration of a rival government in Stanleyville by the end of the year. To prevent a complete collapse of order within the country, the United Nations established a major peacekeeping mission, the United Nations Operation in the Congo (known under its French acronym as ONUC). In addition to a large body of troops (20,000 at its peak strength), a civilian mission was brought in to provide technical assistance to the Congolese government. Initially, ONUC limited its actions to ensuring the safety of Congolese citizens and foreign nationals and refrained from acting against the secessionist states, but the UN ran into trouble in Katanga. The state's leader and head of the locally entrenched Confédération des associations tribales du Katanga (CONAKAT), Moïse Tshombe, at first banned the UN from entering his territory and then greatly limited their peacekeeping efforts. Further issues derived from peacekeepers' attempts to deport foreign mercenaries, many of whom were employed by Katanga.
United Nations response
On 21 February 1961 the UN Security Council passed a resolution permitting ONUC to use military force to prevent civil war, make arrests, halt military operations, arrange ceasefires and deport foreign military personnel. Under the authorisation of this resolution, UN forces launched Operation Rumpunch and Operation Morthor (sometimes referred to as "Round One" of UN-Katangese conflict) with the aim of securing their own positions in Katanga and eliminating the presence of mercenaries. The former, though limited in scope, was largely successful, but the latter failed to achieve its objectives. As Morthor was underway, Special Representative Conor Cruise O'Brien announced, "The secession of Katanga has ended." This statement was quickly realised to be premature; Katanga fought the offensive to a stalemate.
United Nations Secretary-General Dag Hammarskjöld attempted to meet Tshombe for negotiations in Northern Rhodesia, but on the night of 17 September his plane crashed, killing all aboard. Hammarskjöld's untimely death, combined with an overall rise in tensions, helped rally international support for a more robust peacekeeping approach. His replacement, U Thant, was less averse to using military force in the Congo and believed that the UN should intervene in internal Congolese affairs. Thant promptly requested that the Security Council grant ONUC a stronger mandate. This came in the form of a resolution on 24 November, which maintained the goals of previous ONUC resolutions and cleared up any remaining ambiguities surrounding the role and nature of the UN's intervention. It reaffirmed ONUC's ability to detain and deport foreign military personnel and mercenaries with force, described Katanga's secessionist activities as illegal, and declared the UN's support for the central government of the Congo in its efforts to "maintain law and order and national integrity".
Tshombe immediately responded to the resolution by broadcasting an inflammatory speech against ONUC. This was followed by the assault of two UN officials and the murder of two Indian soldiers at the hands of the Katangese Gendarmerie. In turn ONUC's command structure in Katanga, mindful of the new mandate, issued instructions to UN troops to put "an end to Katangese resistance to UN policy by destruction of Gendarmerie and other anti-UN resistance."
Escalation
In December 1961, the UN initiated Operation Unokat (dubbed "Round Two") to ensure ONUC personnel's freedom of movement and reassert their authority in Katanga. Under military pressure, Tshombe was forced to enter serious negotiations with Congolese Prime Minister Cyrille Adoula. On 21 December 1961 Tshombe signed the Kitona Declaration, an agreement whereby he would recognise the authority of the central government and work to reintegrate Katanga into the Republic. However, Tshombe subsequently deferred to the Katangese Parliament and put off any action of reconciliation. In January 1962 the Stanleyville government was finally subdued and the UN was able to refocus its efforts on ending the Katangese secession. By then, contact between the central government and Katanga had broken down and ONUC intelligence reports indicated that the latter was rebuilding its forces.
In August 1962 Thant proposed a "Plan for National Reconciliation" by which Katanga would rejoin a federalised Congo. Adoula and Tshombe both accepted the proposal. Thant was wary of Tshombe's delaying tactics and applied increasing political pressure on the Katangese government to abide by the plan's timetable. Belgian support for Katanga waned as the secession dragged on and the possibility of conflict increased, jeopardising investors' mining interests.
The outbreak of the Sino-Indian War in October raised the potential of all Indian troops being withdrawn from ONUC, putting pressure on UN officials to quickly resolve the secession. The United States government, which had underwritten most of the costs of ONUC, also began pushing for a conclusion, having determined that the operation was financially unsustainable. Still doubting the likelihood of a peaceful resolution, Thant sent Special Representative Ralph Bunche to Léopoldville, the capital of the Congo. There, Bunche worked with Officer-in-Charge of ONUC Robert K. A. Gardiner and UN Force Commander Sean MacEoin to create a plan to achieve freedom of movement for ONUC personnel and eliminate the foreign mercenaries.
By then it was obvious to ONUC that Tshombe did not intend on rejoining the Congo; there were 300 to 500 mercenaries in Katanga (as many as there had been before previous UN operations) and new airfields and defensive positions were being constructed. ONUC personnel and even diplomatic staff faced increasing harassment from Katangese gendarmes. Katangese jets were also attacking ONUC and central government forces, in effect waging civil war. Tshombe was fully aware of the military contingency operation and accused the UN of searching for a pretext to use force against Katanga.
On 27 November the United States and Belgium issued a joint statement, announcing that Thant's plan had failed and calling for increased economic pressure on Katanga. On 10 December Gardiner announced that the UN would take economic measures against Katanga. He wrote a letter to Tshombe, accusing Katanga of failing to institute the Plan for National Reconciliation's provisions or otherwise end its secession. He also demanded that Katangese forces cease military action in northern Katanga, end their supply blockade against UN troops at Sakania, and release detained Tunisian peacekeepers. The letter stated that the UN "would take no offensive military action", but would respond greatly to an attack and take measures deemed necessary to prevent further attacks. The following day Belgian Foreign Minister Paul-Henri Spaak declared that the Belgian government would support the UN or the Congolese government should either one end the Katangese secession through force. He then denounced Tshombe as a "rebel". The United States Department of Defense shortly thereafter dispatched a team to the Congo to evaluate the UN's material requirements for carrying out an offensive and offered military intelligence aid to ONUC. The Katangese responded by organising anti-American demonstrations in Élisabethville.
Prelude
At 10:00 on 24 December 1962, Katangese forces in Élisabethville and along Avenue Tombeur attacked Ethiopian peacekeepers with small arms fire, wounding one. The shooting lasted five hours. The UN maintained that the Ethiopians held their fire, but an Associated Press correspondent reported that they responded with a recoilless rifle. At 11:00 gendarmes shot down an unarmed ONUC helicopter. An Indian member of the crew was mortally wounded while the rest were captured and beaten. A group of ONUC officers was later able to recover the prisoners without incident. Occasional fire continued the next day, and Katangese Foreign Minister Évariste Kimba promised it would cease. The situation was calm in Élisabethville on 26 December, but on 27 December the gendarmes resumed their sporadic fire against UN positions and by the late evening peacekeepers were under attack from roadblocks around the golf course and along Jadotville Road. In reaction to the increasing Katangese hostility, the ONUC Air Division issued Fighter Operations Order 16, directing UN aircraft to retaliate against Katangese aircraft mounting any attack (including against non-UN targets) and to shoot down any others deemed to be carrying "visible offensive weapons, such as bombs or rockets". Tshombe sent a letter to UN representative Eliud Mathu, accusing the peacekeepers of having obstructed the passage of Katangese government ministers on 24 December and engaging in "a general plan" of military operations. Mathu responded by saying that the ministers' movements had been restricted only to ensure their presence so they could order the gendarmes to back down and mediate the release of the helicopter crew.
Mathu proceeded to invite Tshombe to his house so he could be brought to a scene of conflict and see what was occurring. Tshombe agreed, and peacekeepers escorted him to the front lines where he agreed that his own forces were attacking UN positions without provocation. After the tour, Tshombe returned to his residence. Though he initially proclaimed his intent to end the fighting, he went into an adjacent room and telephoned the Katangese forces in Kolwezi. Speaking in Kiswahili, he instructed the Katangese Air Force to raid UN positions. Radio intercepts also revealed to the UN that General Norbert Muke, the commander of the Katangese Gendarmerie, had ordered the air force to bomb the Élisabethville airport on the night of 29 December. 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. This brought relief to some of the UN peacekeepers, mindful that they now had justification to act forcefully against Katanga. Determined to avoid civilian casualties and widespread destruction, the secretary-general sent a wire to the UN Force Commander in the Congo to explain that napalm was to be prohibited from use in combat. In a final attempt to prevent further conflict, Mathu presented Tshombe a document at 11:30 on 28 December for his signature. It stipulated the removal of Katangese roadblocks and the cessation of attacks. Tshombe said he could not sign it without the consent of his ministers and left the meeting. The UN subsequently announced that it would take action to remove the roadblocks on its own. For unknown reasons, Tshombe quietly departed Élisabethville.