Final answer:
The 1974 Carnation Revolution in Portugal led to the independence of Guinea Bissau, Angola, and Mozambique as the new democratic Portuguese government ended colonial wars by recognizing their sovereignty, but subsequent civil wars followed in these nations.
Step-by-step explanation:
Independence Movements and the Portuguese Colonies
The significant 1974 event in Europe that led to the independence of Guinea Bissau, Angola, and Mozambique was the Carnation Revolution in Portugal. The nearly half-century regime of the Second Portuguese Republic, which refused to grant independence to its African colonies, was overthrown by a left-leaning military coup. Unlike other European powers of the time, Portugal had considered its colonies integral parts of the nation. Various independence movements arose within these colonies, many of which received support from communist countries during the Cold War period, despite some movements striving for democracy and others for communism.
Following the coup, the new democratic government in Portugal recognized the unsustainable nature of its colonial wars and thus swiftly granted independence to the aforementioned African nations. However, the acknowledgment of these countries' sovereignty did not spell an end to conflict. Following independence, each of the nations experienced violent civil wars as different factions vied for control and external powers continued to exert influence, reflective of the larger Cold War struggle. In the end, the colonized nations transitioned into independent states, but this was marked by bloodshed and ongoing political turbulence.