The first of three late-20th century emigration waves began in 1961 after the assassination of dictator Trujillo, due to fear of retaliation by Trujillo's allies and political uncertainty in general. In 1965, the United States began a military occupation of the Dominican Republic to end a civil war. Upon this, the U.S. eased travel restrictions, making it easier for Dominicans to obtain U.S. visas. From 1966 to 1978, the exodus continued, fueled by high unemployment and political repression. Communities established by the first wave of immigrants to the U.S. created a network that assisted subsequent arrivals.