sentences:  The movement was engaged in guerrilla warfare 1970–1973.On February 2, 1976, the organisation, together with the Revolutionary Democratic Party of Yemen, the Labour Party, the Popular Vanguard and the People's Democratic Union, founded the National Democratic Front in San'a.On March 5, 1979 the party merged with the other founding parties of the NDF, forming the Yemeni Popular Unity Party.