Since 1980, Peru enters one of its bloodiest eras: an armed group called Sendero Luminoso of Marxist-Leninist-Maoist extraction, led by Abimael Guzmán Reynoso faces a relentless war against the Armed Forces of Peru with the purpose of taking the power. This case study shows how the States response was inadequate to the challenge proposed by Sendero while setting out the reasons why the population was the key factor in stopping the progression of Sendero through the creation of self-defense groups known as Committees of Civil Defense (CDC).