Women have been active in peace movements since at least the 19th century. After the First World War broke out in 1914, many women's organizations became involved in peace activities. In 1915, the International Congress of Women in the Hague brought together representatives from women's associations in several countries, leading to the establishment of the Women's International League for Peace and Freedom. This in turn led to national chapters which continued their work in the 1920s and 1930s. After the Second World War, European women once again became involved in peace initiatives, mainly as a result of the Cold War, while from the 1960s the Vietnam War led to renewed interest in the United States.