Relations between the Congolese prime minister Patrice Lumumba and secretary general Dag Hammarskjöld deteriorated very quickly after the arrival of UN forces in the Congo. At particular issue was the breakaway province of Katanga which Lumumba demanded (with the support of the Soviet Union) should be brought to heel by the UN. His insistence that ‘in its intervention in the Congo the United Nations is not to act as a neutral organisation but rather that the Security Council is to place all its resources at the disposal of my Government’, went to the heart, not just of the UN’s dilemma in the Congo, but to the fundamental principle of impartiality which guided United Nations peace operations at this time. The tone of both Lumumba’s letter and Hammarskjöld’s reply the following day gives a measure of the breakdown in the relationship.