Ambiguous as it was, the phrasing of the UN February 21 resolution left little doubt about the sense of frustration felt by Secretary General Dag Hammarskjöld in dealing with the Katanga secession. Keeping the peace without meddling in the internal affairs of Katanga proved a contradiction UN efforts to act as a mediator between Katanga and the central government met with repeated setbacks. As one reconciliation formula after another was tried and found wanting, it dawned on many people at the UN that the scope of permissible action had to be substantially broadened, which is what the February 21 resolution sought to achieve.

The new mandate provided the basis for Operation Rumpunch on August 28, 1961. As it became clear that Tshombe had no intention of complying with the UN request that mercenaries and European officers be withdrawn from Katanga--a move that he realized would cripple his security forces and quickly bring the collapse of his regime--UN troops at last sprang into action, securing the Katangan post office, radio, and residences of key European and Congolese officials and rounding up mercenaries and European officers. The operation, however, was suddenly halted when the Belgian consul in Léopoldville persuaded local UN officials that he would complete the operation by himself, a pledge that turned out to be a ruse as only regular Belgian officers and not mercenaries were expelled from the province.

Anger and frustration on both sides mounted rapidly. A new UN plan, Operation Morthor, following rapidly after Rumpunch and expected to go into effect on September 13, was no longer merely to rid the province of mercenaries and foreign advisers but to terminate the secession by force. Forewarned of the impending attack, the Katangan gendarmes put up a stiff resistance, while a lone jet fighter strafed the UN troops. News of UN attacks on civilian installations was received with indignation in European capitals. Morthor ended in a total fiasco. It was at this point, on September 17, that Hammarskjöld decided to give up force and once again try to arrive at a negotiated solution with Tshombe. Hammarskjöld never made it to the site of their meeting in Ndola Northern Rhodesia (now Zambia), however shortly before it was due to land, his aircraft crashed into a wooded hillside, killing all passengers.

The next and final phase in the Katangan imbroglio began with the so-called "U Thant Plan," made public on August 10, 1962, and ended with Tshombe's announcement, on January 14, 1963, that "the secession was now terminated." The plan, which offered yet another constitutional formula for reunification, at first met with Tshombe's approval then equivocation ensued, and the work of the joint Léopoldville-Élisabethville commissions soon bogged down. As tensions mounted between UN troops and Katangan gendarmes, little was needed to trigger an explosion. It came on Christmas Eve, when UN troops accused the Katangan forces of shooting down a UN helicopter. On December 28 Tshombe called for a general uprising of the population, to which the UN responded by moving against key points. 287 . This time the tide moved decisively against the gendarmes. In the end, Tshombe had no alternative but to concede defeat. After two and a half years of conflict and crisis, the Katangan secession had finally come to an end. Many of the remaining Katangan gendarmes went into exile in Angola. Others were incorporated into the Congolese military.

Data as of December 1993