The Derg overthrew the Ethiopian Empire and Emperor Haile Selassie in a coup d'état on 12 September 1974, establishing Ethiopia as a Marxist–Leninist state under a military junta and provisional government.

The administration was becoming unpopular across all levels of society due to stagnating quality of life, slow economic development, and widespread human rights abuses.

This awareness grew as the army was frequently used to suppress student protests, peasant uprisings, and regional revolts in Ogaden, Bale, and Eritrea.

The military mutinies that triggered the 1974 Ethiopian Revolution began with demands for better working conditions and wages for troops stationed in remote regions like Ogaden, Negele, and western Eritrea.

[17] On 12 September 1974, Haile Selassie and his government were overthrown by the Derg, a non-ideological committee of low-ranking officers and enlisted men in the Ethiopian Army who became the ruling military junta.

On 21 March 1975, the Derg abolished the monarchy and adopted Marxism–Leninism as their official ideology, establishing themselves as a provisional government for the process of building a socialist state in Ethiopia.

[21] The Derg did not fully establish their control over the country, and the subsequent power vacuum led to open challenges from numerous civilian opposition groups.

In 1976, the Derg instigated the Qey Shibir (Ethiopian Red Terror), a campaign of violent political repression primarily targeting the EPRP and later the All-Ethiopia Socialist Movement (MEISON), in an attempt to consolidate their power.

[22] By August 1977, the EPRP and MEISON were devastated, with their leadership either dead or fleeing to the countryside to continue their activities in stronghold areas, but despite this, the Derg did not successfully consolidate their power as much as hoped.

Ironically, the majority of the Qey Shibir's estimated 30,000 to 750,000 victims are believed to be innocents, with the violence and collateral damage shocking many Ethiopians into supporting rebel groups.

When the Derg came to power, Eritreans were widely subjected to increasing repression and economic disruption as the government sought to crush the elusive insurgency in vain.

[15] The early 1970's saw the Somali liberation movement for the Ogaden region continue to gain momentum off the foundations of the Nasrallah insurgency which had fought a major revolt from 1963 to 1965 against Emperor Haile Selassie's empire.

[24] The many veteran insurgents and young intelligentsia from the Ogaden region within Siad Barre's government lobbied for Somalia to support the resumption of the armed struggle during the 1970s.

[25] By June 1977, the Western Somali Liberation Front (WSLF) had been successful in forcing the Ethiopian army out of much of the Ogaden and into the major urban strongholds of Jigjiga, Dire Dawa and Harar.

President of Somalia Siad Barre decided to intensify the war by involving the Somali army as he believed it would allow the WSLF to press home their growing victories and enable the complete secession of the Ogaden.

Many member of the ruling elite were deeply opposed to the idea of loosening control on the rebellious southern regions conquered under Menelik II.

[15] During the early 1980s the Ethiopian government rendered the Somali inhabited Ogaden region a vast military zone, engaging in indiscriminate aerial bombardments and forced resettlement programs.

[30] Hundreds of thousands fled economic misery, conscription and political repression, and went to live in neighboring countries and all over the Western world, creating an Ethiopian diaspora community for the first time in its history.

On 28 May 1991, Mengistu's government was overthrown by its own officials and a coalition of rebel forces, the Ethiopian People's Revolutionary Democratic Front (EPRDF), after their bid for a push on the capital Addis Ababa was successful.

There was some fear that Mengistu would attempt to fight to the bitter end for the capital, but after diplomatic intervention by the United States, he fled to asylum in Zimbabwe, where he still resides.

[36][37] It also had impacts on land and agriculture: the reversal of the former feudal system and implementation of nationalized reforms led peasants to lose 75% of their production to landlords.