In April 1965 the democratically elected Dominican president Juan Bosch was ousted and the militarily installed president Donald Reid Cabral in office. A second coup prompted the military loyal to the dictator Reid to initiate an armed campaign against the “constitutionalist” rebels.

Allegations of communist support for the rebels led to a United States intervention in the conflict (Operation Power Pack). Americans and Dominicans skirmished several times but fought only one battle where 8 US and 67 Dominicans were killed. 

Source:Wikipedia