Both the EPRP and another party, the All-Ethiopia Socialist Movement (MEISON) were enthusiastic supporters of the student-led 1974 Ethiopian Revolution that eventually led to the toppling of Emperor Haile Selassie and abolishing the monarchy the following year.

However, following the rise of Mengistu Haile Mariam to power as leader of the ruling Derg, the military junta that had taken control of Ethiopia, ideological conflict developed between the various groups.

[5] Part of their rivalry was based on Marxist theory: for the Ethiopian Revolution to be an "authentic" one, there needed to be a vanguard party, and both groups wanted that role.

The TPLF brought two of its veteran companies from the west, and in a fierce counter-attack forced the EPRP fighters back to their bases at Mount Asimba.

Eventually, many party members found their way to Gondar, continuing their struggle against both the Derg and the TPLF until Mengistu's government final defeat at the end of the Ethiopian Civil War in 1991.