Originally trained as an electrician, he joined the African Party for the Independence of Guinea and Cape Verde (PAIGC) of Amílcar Cabral in 1960 and soon became a key player in the territory's guerrilla war against Portuguese colonial rule.

By contrast, most of Guinea-Bissau's army officers, with whom Vieira had a tense relationship throughout his career, are members of the Balanta ethnicity, which dominates the country.

[5] As the war in Portuguese Guinea intensified, Vieira demonstrated a great deal of skill as a military leader and rapidly rose through its ranks.

The guerrilla war began to turn against the Portuguese as expenditure, damages and loss of human lives remained a burden for Portugal.

Following the coup d'état in Portugal in 1974, the new Portuguese revolutionary government which overthrew Lisbon's Estado Novo regime began to negotiate with the PAIGC.

Through pressure from groups like the Democratic Front (FD) led by Aristide Menezes, the ban on political parties was lifted in 1991 and elections were held in 1994.

Vieira was re-elected for another four-year term as President of PAIGC in mid-May 1998 at a party congress, with 438 votes in favor, eight opposed, and four abstaining.

[9] Vieira dismissed military chief of staff Ansumane Mané on 6 June 1998, accusing him of smuggling arms to Casamance separatist rebels in Senegal.

[10] Mané was widely supported by soldiers and war veterans, as well as by some of civil society and members of the political opposition to Vieira's government.

Although Vieira's supporters had collected 30,000 signatures for a petition urging him to run for president, he did not immediately confirm his intention to do so, saying that he was returning "to re-establish [his] civic rights and to register to vote in the coming elections" and that he wanted to contribute to peace and stability.

[18] Although many considered Vieira to be ineligible because he had been living in exile and because of legal charges against him pertaining to the 1985 killings of suspected coup plotters, he was cleared to stand in the election by the Supreme Court in May 2005, along with Yalá.

Vieira held a press conference later in the day, in which he said that the attack had "a single objective – to physically liquidate me", while also asserting that "the situation is under control".

[27] In a subsequent radio interview, he told citizens that they can count on the unconditional support of the president and questioned whether the country would continue like this, whether the state could do its job without interference, he accused the Army Chief of Staff, General Batista Tagme Na Waie, of being responsible for the attempted coup d'état and endangering stability, peace and democracy in the country.

He claimed that during a meal with the forensic pathologist investigating the case, he was informed that Vieira was in fact hacked to death by soldiers wielding machetes at his mother-in-law's house.

According to this account, Vieira survived an explosion and the collapse of the presidential villa's roof and was then shot when he emerged, injured, from the damaged building; nevertheless he remained alive until being taken to his mother-in-law's house and hacked to death.

Forsyth attributed the bloody events to mutual hatred between Vieira and Tagme Na Waie, and he characterized both of them as violent people.

The eulogy for Vieira stressed his importance in the war for independence and his adoption of multiparty politics and liberal economic reforms in the early 1990s.

The corpse was again buried in the Fortaleza de São José da Amura along with other heads of state such as Malam Bacai Sanhá and Kumba Ialá, in the fortress where the General Staff of the Guinea-Bissau Armed Forces works.