In 1972, Belgrade faced smallpox outbreak, the last major outbreak of smallpox in Europe since World War II. Between October 1977 and March 1978, the city hosted the first major gathering of the Organization for Security and Co-operation in Europe with the aim of implementing the Helsinki Accords from, while in 1980 Belgrade hosted the UNESCO General Conference. Josip Broz Tito died in May 1980 and his funeral in Belgrade was attended by high officials and state delegations from 128 of the 154 members of the United Nations from both sides of the Iron Curtain, based on which it became one of the largest funerals in history.