Since 1961, with the beginning of the colonial wars in its overseas territories, Portugal had begun to incorporate black Portuguese Africans in the war effort in Angola, Portuguese Guinea, and Portuguese Mozambique based on concepts of multi-racialism and preservation of the empire. African participation on the Portuguese side of the conflict ranged from marginal roles as laborers and informers to participation in highly trained operational combat units, including platoon commanders. As the war progressed, use of African counterinsurgency troops increased; on the eve of the military coup of 25 April 1974, Africans accounted for more than 50 percent of Portuguese forces fighting the war. Due to both the technological gap between both civilizations and the centuries-long colonial era, Portugal was a driving force in the development and shaping of all Portuguese Africa since the 15th century.