The Guinea-Bissau War of Independence (), or the Bissau-Guinean War of Independence, was an armed independence conflict that took place in Portuguese Guinea from 1963 to 1974. It was fought between Portugal and the African Party for the Independence of Guinea and Cape Verde (Partido Africano da Independência da Guiné e Cabo Verde, PAIGC), an armed independence movement backed by Cuba, the Soviet Union, and Yugoslavia. The war is commonly referred to as "Portugal's Vietnam" because it was a protracted guerrilla war which had extremely high costs in men and materiel and which created significant internal political turmoil in Portugal. After the assassination of PAIGC leader Amílcar Cabral in January 1973, the military conflict reached a stalemate: Portuguese forces were largely confined to major cities and various fortified bases and were patently unable to dislodge PAIGC from the so-called liberated zones. In September 1973, the PAIGC-dominated People's National Assembly unilaterally declared the independence of a new Republic of Guinea-Bissau; the declaration was recognised by several foreign countries. After the Carnation Revolution, the new Portuguese government agreed to grant independence to Guinea-Bissau in September 1974 and to Cape Verde a year later. PAIGC thus became the first sub-Saharan African liberation movement to achieve independence – if only indirectly – through armed struggle. Background Portuguese colonialism Portuguese Guinea (as well as the nearby Portuguese Cape Verde archipelago) had been claimed as a Portuguese territory since 1446 and was a major trading post for commodities and African slaves during the 18th century. However, the mainland was not fully "pacified" until the late 1930s, by which time the Portuguese regime of António de Oliveira Salazar was preoccupied with the development of its Angolan and Mozambican colonies. There were various changes to the colonies' legal status and governance structures during this period and in subsequent decades, but they were primarily "cosmetic" in effect. In the phrase of Patrick Chabal, Guinea was "the smallest and most backward of the Portuguese colonies", partly due to its inhospitable climate and apparent dearth of natural and mineral resources. There were few European settlers in Guinea, and the footprint even of the Portuguese administration was minimal and "crude", remaining centralised under the governor. Portugal invested little in the colony and made only minor gestures towards promoting its economic and social development. Nonetheless, a colonial economy existed on the Guinean mainland, controlled primarily by the Companhia União Fabril and consisting primarily