Portuguese History
Portugal derives its name from ancient Portus Cale (now Oporto), at the mouth of the Douro River, where the Portuguese monarchy began.
The country's early history is indistinguishable from that of the other Iberian peoples. Lusitanians were successively overrun by Celts, Romans, Visigoths, and Moors (711). In 1094, Henry of Burgundy was given the county of Portugal by the king of Castile and León for his success against the Moors; his son, Alfonso I (Alfonso Henriques), became king and achieved independence for Portugal in 1143, beginning the Burgundy dynasty. By the mid-13th century, the present boundaries of Portugal were established, and Lisbon became the capital.
During the reign of King John (João) I, the founder of the powerful Aviz dynasty and husband of the English princess Philippa of Lancaster, the Portuguese defeated the Spanish in a war over the throne (1385), established a political alliance with England (by the Treaty of Windsor in 1386) that has endured to the present day, and inaugurated their most brilliant era.
Prince Henry the Navigator (Henrique o Navegador), a son of John I, founded a nautical school at Sagres, where he gathered the world's best navigators, cosmographers, geographers, and astronomers and commenced a series of voyages and explorations that culminated in the formation of the Portuguese Empire.
In the 15th and 16th centuries, the golden age of Portugal, Portuguese explorers sailed most of the world's seas; made the European discovery of the Cape of Good Hope, Brazil, and Labrador; founded Portugal's overseas provinces in western and eastern Africa, India, Southeast Asia, and Brazil; and poured the vast riches of the empire into the homeland. 
In 1580–81, Philip II of Spain, claiming the throne, conquered Portugal and acquired its empire, but national sovereignty was restored by the revolution of 1640 and the accession of John IV, founder of the Bragança dynasty, to the Portuguese throne.
John IV ushered in Portugal's silver age, the 17th and 18th centuries, when the wealth of Brazil once more made Lisbon one of the most brilliant of European capitals. The city was largely destroyed by a great earthquake in 1755 but was subsequently rebuilt.
Since 1661, Portugal had been a British ally; in effect, Portugal was incapable to defend her vast colonial empire by herself; the British alliance permitted her to hold on to it. Since the Treaty of San Ildefonso, 1796, Spain and France were allies. In 1800, Napoleon ultimatively demanded Portugal to enter into an alliance with France - which would have been directed against England and would have resulted in Portugal being disconnected from her colonies. Portugal refused.
A Franco-Spanish force invaded Portugal in May 1801; after inflicting a defeat on the Portuguese, the city of Olivenza was taken. Spanish minister Godoy reported to Madrid that he had picked Oranges near Olivenza; thus the expression "War of the Oranges"; his announcement that he would march on Lisbon next, was not executed. In June, the Treaty of Badajoz was signed, according to which Portugal entered into an alliance with France, ceded Olivenza to Spain and Brazilian territory bordering on French Guyana to France.
The Treaty of Badajoz did not provide a lasting solution. Portugal was not sincere in implementing her obligation to close her borders to British imports. In 1807, Spain and France, in the Treaty of Fontainebleau, agreed to invade and partition Portugal. 
During the Napoleonic wars, Portugal, faithful to its British alliance, was the base of British operations against the French in the Iberian Peninsula. The royal family, however, withdrew to Brazil, and from 1807 to 1821, Rio de Janeiro was the seat of the Portuguese monarchy. In 1822, Brazil, ruled by Pedro, the son of King John VI of Portugal, formally declared its independence; Pedro became Emperor Pedro I of Brazil but was deposed in 1831.
The Bragança dynasty, which had ruled Portugal since 1640, came to an end with the revolution of 1910, when the monarchy was replaced by a republican regime. Lack of stability under the new republic led to a military dictatorship in 1926. Marshal António Carmona served as president from 1926 to 1951.
António de Oliveira Salazar, brought to the government in 1928 as minister of finance, emerged as Portugal's prime minister in 1932. In 1933, Salazar proclaimed a new constitution, which consolidated his regime and established Portugal as a corporative state. During World War II, Portugal supported the Allies but did not take part in combat; it subsequently became a member of NATO.
Despite its reduced status as a European power, Portugal attempted to maintain its overseas empire, especially its resource-rich African provinces. In 1961, Portugal surrendered Goa, Daman, and Diu to India. In the same year, uprisings in Angola began, organized by the Union of Angolan Peoples in protest against Portugal's oppressive policies in the territory. These uprisings led to serious disagreements between the UN and Portugal; following Portugal's refusal to heed its recommendations for liberalization of policies with a view toward eventual self-government, the UN General Assembly passed a resolution in 1965 calling for a worldwide economic and arms boycott of Portugal in order to force it to grant independence to its African dependencies. Subsequently, the Assembly passed a number of resolutions condemning Portugal for its policies in its African territories. Meanwhile, guerrilla movements in Angola, Mozambique, and Guinea-Bissau were met by a steadily increasing commitment of Portuguese troops and supplies.
Salazar, who served as prime minister of Portugal from 1932 to 1968, died in July 1970 at the age of 81. When he was incapacitated in September 1968, he was succeeded by Marcello Caetano. The unwillingness of the Caetano regime to institute democratic and economic reforms, coupled with growing discontent over the continuance of the ever more costly colonial war in Africa, led to a military coup by the left-wing Armed Forces Movement in April 1974. 
Broad democratic liberties were immediately granted and opposition political parties legalized, while the corporate state apparatus was gradually dismantled. A decolonization program was also begun, resulting by November 1975 in the independence of all of Portugal's African provinces.
The first provisional coalition government came to power in May 1974, with Gen. António Sebastião Ribeiro de Spínola, whose book Portugal and the Future had played a key role in focusing antiwar sentiment among the military, as president. In September 1974, after a power struggle with the leftist forces, Gen. Spínola resigned and was replaced by Gen. Francisco da Costa Gomes. Following an unsuccessful right-wing coup attempt in March 1975, Gen. Spínola was forced to flee the country, along with a number of officers. The continued dissension between right and left—and between Communist and Socialist factions on the left—was evidenced by the numerous provisional governments that followed the coup.
In April 1975, general elections were held for a Constituent Assembly, whose task was to draw up a new constitution. Legislative elections were held in April 1976 and presidential elections in June. Gen. António dos Santos Ramalho Eanes was elected president, and the leader of the Portuguese Socialist Party, Mário Alberto Nobre Lopes Soares, became prime minister. Mainly as a result of policy differences within the governing coalition, this administration fell in July 1978 and was replaced by a caretaker cabinet.
sources:- World History at KMLA and Encyclopedia of the Nations