After the withdrawal, UNEF remained for ten years as a buffer between the Egyptian and Israeli forces in Sinai and the Gaza strip. UNEF's presence brought calm to the region. Illegal passage over the borders, firing and various violations took place, but they were infrequent and not serious. UNEF was trusted by both sides, but this favourable situation could not prevail against new unfavourable political developments. The latter forced its withdrawal, and the 1967 war followed. General Nils Sköld (1921-96), who ended his career as Commander-in-Chief of the Swedish Army in 1976-84, took part as a junior staff officer in organising the first and second Swedish battalions in 1956-7, and in 1959 served in the sixth battalion as a pany commander. It is thus with special authority that he writes the history of UNEF, with emphasis on the Swedish participation which involved a total of 12,000 soldiers. The Swedish experience from serving with UNEF is extensively analysed. The principles on which UNEF operated were formulated by Dag Hammarskjöld, and the experience drawn from the operation have been used in subsequent peacekeeping operations. Most of this experience is valid to this day.