Shortly thereafter seven Lumumbists, including the first President of Orientale Province, Jean-Pierre Finant, were executed in South Kasai for "crimes against the Baluba nation". Gizenga's soldiers then shot 15 political prisoners in retaliation, including Lumumba's dissident Minister of Communications, Alphonse Songolo. United Nations escalation and the end of the Katangese secession Since its initial resolution of July 1960, the UN had issued further resolutions calling for the total withdrawal of Belgian and mercenary forces from Katanga in progressively stronger terms. By 1961, ONUC comprised nearly 20,000 men. Although their mandate prevented them from taking sides, ONUC had a mandate to arrest foreign mercenaries wherever they encountered them. In September 1961, an attempt to detain a group of Katangese mercenaries without violence during Operation Morthor went wrong and turned into a fire-fight. ONUC's claim to impartiality was undermined in mid-September when a company of Irish UN troops were captured by numerically superior Katangese forces following a six-day siege in Jadotville. Katanga proceeded to hold the Irishmen as prisoners of war, a development that deeply embarrassed the UN mission and its proponents. On 18 September 1961, Hammarskjöld flew to Ndola, just across the border in Northern Rhodesia, to attempt to broker a cease-fire between UN and Katangese forces. His aircraft crashed before landing at Ndola Airport, killing him and everybody else on board. In stark contrast to Hammarskjöld's attempts to pursue a moderate policy in the Congo, his successor U Thant supported a more radical policy of direct involvement in the conflict. Katanga released the captured Irish soldiers in mid-October as part of a cease-fire deal in which ONUC agreed to pull its troops back—a propaganda coup for Tshombe. Restated American support for the UN mission, and the murder of ten Italian UN pilots in Port-Émpain in November 1961, strengthened international demands to resolve the situation. In April 1962, UN troops occupied South Kasai. On the night of 29/30 September 1962, South Kasai military commanders launched a coup d'état in Bakwanga against the Kalonjist regime. On 5 October 1962, central government troops again arrived in Bakwanga to support the mutineers and help suppress the last Kalonjist loyalists, marking the end of South Kasai's secession. Resolution 169, issued in November 1961, called for ONUC to respond to the deteriorating human rights situation and prevent the outbreak of full-scale civil war. The resolution "completely rejected" Katanga's claim to statehood and authorised ONUC troops to