National Front
In the 50s increased migration to cities due to the intensification of partisan conflict (liberal-conservative) that were vying for power. The conflict that was expressed from the 30s as a result of social tensions escalated after the death of Gaitan on April 9, 1948 and acquired different characteristics in different regions of the country. Guerrilla groups appeared in mountainous areas and remote rural areas and in populated eastern plains. Due to the pressure exerted by these groups destabilizing established a military dictatorship then in order to permit monitoring in conflict zones. This government was succeeded by a two-party system between liberals and conservatives since 1958 known as the National Front.
In 1960 Communist influence was a different character to the conflict. Thousands of families left their land and were organized in the mountains where many groups were established as armed. The violence began to emerge as the confrontation between Marxist Leninist guerrillas and the military. The ELN (National Liberation Army) emerged in 1965, the EPL (Popular Liberation Army) in 1967 and finally in 1973 made his first appearance on M-19. In 1974, the National Front and returned to the system of choice.
During this period, drug smuggling and begin to consolidate their operations in the country. In the 1982-1986 presidential term are held the first peace negotiations with guerrilla groups, these are the first results with the demobilization of the M-19 and the EPL during the administration of Virgilio Barco (1986-1990). Given the need to reform the Constitution of 1886 a group of university students held a plebiscite in 1990.