Former Brigadier General Ansumane Mane attempted a coup against President Joao Bernardo Vieira, who has ruled Guinea-Bissau since 1980. Mane accused the President of corruption and leading the nation into poverty. Vieira fired Mane from command of the armed forces on charges of selling weapons to the Casamance rebels of southern Senegal. The army rebellion also may have originated in part due to the government's inability to properly pay its soldiers.

Senegal's apparent interest in saving the Vieira government stemmed partly from a desire to prevent a government friendly to the Casamance rebels from ruling Bissau. Also, after the intervention began, Senegalese forces began a     campaign against Casamance forces in based in northern Guinea-Bissau. Senegal apparently took advantage of the upheaval in Bissau in order to pursue its own interests.

A military coup was attempted on June 7, 1998. The rebels failed to oust the government, which then received significant aid from neighboring Senegal and Guinea-Conakry. Nearly 1,200 Senegalese and 400 Conakry troops flew into Bissau to help suppress the rebellion. Despite the efforts of government loyalists and the foreign troops, the rebellion against President Vieira not only continued, but grew as the countryside erupted in revolt against the government as guerilla veterans of Bissau's War of Independence took up arms against the the President, citing the nation's poverty and government corruption, rather than a fondness for Mane.

Fighting in the capital caused many of the 300,000 inhabitants to flee the city, while artillery duels created great damage to the downtown areas.

The two sides agreed to a cease-fire July 26, while negotiations continued with Portuguese assistance. Violence ruptured the cease-fire several times, but usually in isolated incidents as on October 19, when both sides engaged in artillery duels in Bissau.

Vieira and Mane signed a peace agreement November 2, 1998 in Abuja, Nigeria. After intense negotiations involving the leaders of Gambia and Nigeria, the two sides agreed to an arrangement which called for new elections in March and the pullout of Senegalese and Guinea-Conakry troops who were replaced by a regional peacekeeping force. The terms of the peace deal established an interim government of national unity featuring supporters of President Joao Vieira and of the rebel faction. The new 10-person government, were to have led the country until elections scheduled for later in 1999.

The peace deal showed serious signs of breaking down in February, 1999 as both sides engaged in renewed fighting, but further work on the part of Togolese diplomats soon halted the combat.

After the Senegalese and Guinea-Conakry troops left, forces from the West African organization called ECOMOG (Economic Community of West African States), moved in to keep the peace.

On Thursday, May 6, 1999, Mane's forces struck out against the government troops, capturing Bissau and forcing Vieira to flee to a foreign embassy for safety. Apparently, Mane was concerned that ECOMOG had failed to disarm Vieira's Presidential Guard, and feared the repercussions of this supposed breach of the peace pact. Vieira's Presidential Guard was formed from members of his own ethnic group, the Pepel.

 Devastation in the capital city.

The overthrow of President Vieira.

Possible political and military tension between the new Bissau government and neighboring Senegal and Guinea-Conakry.

Elections were held and the new civilian government of President Kumba Yalla (the first democratically elected leader in Bissau history) took power in February 2000.