The term "ecumenical" stems from the Greek oikoumene, meaning "the inhabited world." The ecumenical movement has many facets. Evangelism brings diverse Christians into contact and cooperation in order to proclaim the gospel, as in the crusades of Billy Graham. Youth ministry and education have been addressed through non-denominational groups such as the YMCA, founded in 1844. Compassion and aid to persons in need has been especially urgent in the wake of World Wars I and II and subsequent conflicts or natural disasters. Doctrinal differences between the Christian traditions have been the subject of numerous dialogs. Structural union through church mergers has taken place between groups within a denominational family, or across denominational lines to make a national Protestant Church, such as the United Church of Canada, the Church of South India, and the Uniting Church of Australia. Ecumenism has many antecedents but the modern movement began with Edinburgh 1910, which in turn led to the World Council of Churches in 1948. Vatican II (1962-1965) marked a new era for ecumenical relations between Roman Catholicism and other Christian churches.