The MNLF was founded as a splinter group of the Muslim Independence Movement on October 21, 1972.

MNLF officially claims that its ideology is egalitarianism, and the organization is a secular movement, unlike its splinter group the Moro Islamic Liberation Front.
As a reaction to the declaration of Martial Law, rebels who later identified themselves as belonging to the “Mindanao Revolutionary Council for Independence” led by traditional and secular leaders commenced an armed uprising against the government by attacking Marawi City in Lanao del Sur on 21 October 1972. They seized the airport, the headquarters of the Philippine Constabulary and the Mindanao State University. Government forces arrived and reinforced the beleaguered city on 24 October and the rebels retreated to the hills from where they appealed for support from other Muslim groups and soon the Muslim armed struggle against the government spread throughout Muslim Mindanao and Sulu. Although the MNLF did not participate in the Marawi City uprising that resulted into the death of seventy-five people, the bloody incident hastened its timetable for the commencement of its armed offensive against the government.

Sources: Daniel Cassman (August 14, 2015). “Moro National Liberation Front”. Mapping Militant Organizations – Stanford university.

“Asia Times Online :: Moro leader looks for united front”. Archived from the original on January 31, 2013
T. J. S. George, Revolt in Mindanao (Kula Lumpur: Oxford University Press, 1980),208