I can’t speak about the French involvement, but I hope I can help when it comes to the Belgians and why they supported the Katangese.

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Traditionally, the Katanga secessionist movement was viewed as a tool of colonial officials and multinational mining industries against Patrice Lumumba’s radical central government. Although that’s a simplistic view which dramatically understates the role of the Katangese themselves, it’s not wrong to say that Belgium did have considerable interests in supporting Katanga.

By the end of WWII, 70% of the Congolese economy was controlled by Soceiété Générale de Belgique and its affiliates. The Katanga mines in particular were dominated by one of these affiliates, the Union Miniére du Haut-Katanga (UMHK), whose officials had been entrenched within the Katangese administration for decades. By 1959, Katanga was responsible for 50% of Congolese income and 75% of mineral production.

But by that time, political realities meant that Belgium could no longer directly govern the Congo. That didn't mean Belgium was prepared to sacrifice their economic interests. Instead they committed to a gradual withdrawal which mean they could influence the Congo from behind the curtain. While the native Congolese would have political leadership, the Belgians planned to keep their administrators behind alongside 1,000 Belgian officers to lead the 25,000 strong Congolese army.

Basically, the Belgians were ready for some neocolonialism.

In their ideal world, a pro-western government would continue to give Belgium and its mining conglomerates the resources they needed without the hassle of colonial governorship. General Janssens summarised it best only five days after Congo was granted independence, when he gathered the Congolese army and wrote “before independence = after independence” on a black board.

But the Congolese army had already been brimming with discontent and Janssens had pushed them over the edge. Within hours, they had mutinied and the Congo crisis began. Despite efforts by Lumumba to control the situation, further mutinies and violence began to spread across the country. The Belgians took the opportunity to 'offer' military 'assistance', much to Lumumba's annoyance.

Belgium already had a dim view of Lumumba. He was the exact opposite of what they had been hoping for. When King Baudouin decided to celebrate Belgian rule and the infamous King Leopold II, Lumumba reacted by delivering a fiery speech where he denounced Belgian colonialism as a ‘humiliating slavery’. Not only was he an avowed pan-Africanist, but his government was already mulling taking over both the Catholic school network and the mining industry.

This was in contrast to the president of Katanga, Moïse Tshombe. His political party, Conakat, supported Katangese autonomy within a federal Congo. The UMHK had been funding them for years and they had been supported by European advisers, especially in the months before independence. Compared to Lumumba's central government, Tshombe was a far more attractive ally for the Belgians.

So by July 10 1960, the Belgian army intervenes under the excuse of protecting European lives and property. The next day, Tshombe declared Katangese independence. He was assisted by Belgian advisers, who helped to draft both Katanga’s declaration of independence and its constitution.

The Belgian government was split over supporting the Katangese secession. The king supported the movement alongside the prime minister's chief aide and the consul in Elisabethville. However, both Belgian's representative at NATO and the foreign minister were against it. The Suez Crisis had occurred only a few years ago, and they were concerned that the Americans might condemn Belgium in the same way they had previously condemned Britain and France.

Ultimately, the prime minister established the Mission Technique Belge to funnel aid towards the Katangese, but refused to grant official diplomatic recognition. Belgian officers helped to train the Katangese army in the early months, and Belgian economic advisers lent their assistance towards the establishment of a Katangese central bank. Mining conglomerates began paying taxes towards Tshombe instead of Lumumba, and the UMHK alone gifted 1.25 billion francs to Tshombe’s new government.

A few days later, UN Resolution 143 was passed. It called for Belgian withdrawal and sanctioned UN military action. However, they were reluctant to intervene in Katanga since they considered it an “internal affair”. A frustrated Lumumba eventually requested Soviet assistance but this led to political rivals removing him from government in September 1960. Many of his followers fled to Stanleyville where they established a rebel government, and by January 1961 Lumumba had been murdered in Katanga by Belgian mercenaries.

By now, the Belgians were dealing with a very different situation.

Firstly, the new Congolese government was much more pro-western, and Cyrille Adoula in particular was strongly supported by the Americans. Secondly, the brutal murder of Lumumba led to an international outcry. UN Resolution 161 was passed, empowering peacekeepers to advance into Katanga and forcefully expel the Belgians. Lastly, the rebel government in Stanleyville was receiving strong support from communist powers such as the Soviet Union and Cuba, which meant that the western powers wanted to forge a strong anti-communist front between Leopoldville and Elisabethville.

All of this means the Belgians didn't have any good reason to continue supporting Katanga. They became convinced that their economic interests in Katanga could be better served through a federal government in Congo. So, they provided the new Congolese government with substantial financial and military aid. At the same time, they attempted to encourage Tshombe to accept Katanga’s peaceful reunification with Congo. As for the UN, hundreds of Belgian mercenaries and advisers had been captured following military action. Katanga defied expectations of an immediate collapse, but by January 1963 they had been defeated by UN military action.

In summary, the Belgians were primarily motivated by a desire to protect their economic interests in Congo. Lumumba’s government was perceived as a radical threat to these interests. When crisis broke out, a pro-Katanga lobby amongst sympathetic politicians and the mining industries led to Belgian support for a friendly government in Katanga. Following a coup against Lumumba, the Belgians began to view a federal Congo as a more valuable partner than Katanga alone. A new pro-western Congolese leadership, the threat of a pro-Soviet rebel government, and an emboldened UN intervention against Katanga all meant that Belgium no longer viewed their secession as worth supporting.

Sources and further reading

Boehme, O. ‘The Involvement of the Belgian Central Bank in the Katanga Secession, 1960-1963’, African Economic History (2005)

Larmer, M. & Kennes, E. ‘Rethinking the Katangese Secession’, The Journal of Imperial and Commonwealth History (2014)

Larmer, M. & Kennes, E. The Katangese Gendarmes and War in Central Africa: Fighting Their Way Home (2016)

Nzongola-Ntalaja, G. The Congo, From Leopold to Kabila: A People’s History (2007)

Schmidt. E. Foreign Intervention in Africa: From the Cold War to the War on Terror (2013)