The study is in two parts. The first is chronological, and begins with the establishment of the UN Emergency Force (UNEF Il) after the October War of 1973; the political antecedents involving the Secretary-General, the Security Council and the countries approached for contributions; the interposition of "mini-battalions" between the Egyptian and Israeli front lines; the UNEF build-up, the complex separation of forces, the establishment of the blue helmets in the buffer-zones, routine activities and incidents, and finally - after a peace treaty - the winding-up of the UN force. The despatch of a Swedish advance guard to a new peacekeeping force in Lebanon in 1978 is also described. The three levels and locations of command - UN headquarters in New York, UNEF headquarters, and the fourteen successive Swedish contingents - are all given their due weight. The second part is analytical, looking not only at the course of events, but at the different concerns of the military staff: operational, logistical and personal. The final chapter sums up the essential experience and lessons of the operation, with some proposals for improvements.