African nationalism first emerged as a mass movement in the years after World War II as a result of wartime changes in the nature of colonial rule as well as social change in Africa itself. Nationalist political parties were established in almost all African colonies during the 1950s and their rise was an important reason for the decolonisation of Africa between 1957 and 1966. However, African nationalism was never a single movement and political groups considered to be African nationalists varied by economic orientation and degrees of radicalism and violence. Nationalists leaders struggled to find their own social and national identity following the European influence that controlled the political landscape during the colonial occupation.