Key points on Latin America's longest conflict and the peace process.
Disputed origins
There is disagreement on when and why war broke out. In a country covered in mountains and jungle, where the government's presence is often weak, rural poverty has played a central role. Most historians trace the conflict to the 1960s, when several leftist guerrilla groups rose up against a government they accused of subjugating peasants and the poor. Some go back to the 1940s and a period known as "La Violencia" (the violence), an eruption of bloodshed in the countryside following the assassination of leftist presidential candidate Jorge Eliecer Gaitan. Others date it to peasant uprisings in the 1920s.
Key players
Founded in 1964, the Revolutionary Armed Forces of Colombia (FARC) is the country's oldest and largest leftist guerrilla group. But there have been many players in the conflict.
Others include:
• The National Liberation Army (ELN). Still active. Has agreed to peace talks.
• The April 19 Movement (M-19). Demobilized in 1990.
• The People's Liberation Army (EPL). Demobilized in 1991.
• In the 1980s, a right-wing paramilitary group, the Self-Defense Forces of Colombia (AUC), began fighting the guerrillas. Funded by large landholders, the group sometimes collaborated with the army. It was disbanded between 2003 and 2006, though remnants continue to operate as criminal gangs.
• Drug cartels have also fueled the violence since the 1980s.
Long list of victims
The conflict has left 260,000 people dead and forced nearly seven million from their homes in the past five decades. Another 45,000 are missing.
Atrocities on all sides
Massacres, kidnappings, scorched-earth campaigns and extrajudicial killings have been hallmarks of the conflict, with atrocities committed on all sides.
FARC:
• Massacres such as one in the town of Bojaya in 2002, when guerrillas killed at least 79 people sheltering in a church.
• Kidnapping and holding hostages, such as then presidential candidate Ingrid Betancourt, abducted in 2002 and rescued in 2008.
• Accused of a 2003 car bombing at a social club in Bogota, which killed 36 people.
ELN:
• Mass hostage seizures such as the hijacking of Avianca Flight 9463 in 1999.
• Massacres such as the one in Machuca in 1998, when rebels dynamited an oil pipeline. Burning oil set the village alight and killed 84 people.
M-19:
• Besieged the Supreme Court building in 1985, leaving some 100 people dead.
Paramilitaries:
• Wiped out entire villages, often blasting loud music as militia members killed and raped victims. In one gruesome case, the El Salado massacre in 2000, 60 people were killed.
Army:
• Executed hundreds of civilians and reported them as rebels killed in combat in the so-called "false positives" scandal.
Peace efforts
The first talks were launched in March 1984 but broke down several years later, and subsequent peace efforts collapse in 1991 and 2002. But after four years of new negotiations, the government and FARC reach a definitive ceasefire and disarmament agreement on June 23, 2016. They signed a historic peace deal on September 26, with Santos and Timochenko using pens made from bullet casings. The six-point accord provided for the FARC's full disarmament and its transformation into a political party, the creation of courts to judge crimes committed during the conflict, crackdowns on drugs trafficking along with help for farmers, and land reform.
But Colombia was plunged into uncertainty when voters on October 2 rejected the accord by a razor-thin majority of 56,000. Santos has scrambled to salvage the peace deal, holding meetings with leading opponents of the accord who protested that it was "weak" and gave impunity to the rebels.
