The objective of the offensive was to initiate a popular revolution to overthrow the Revolutionary Government Junta (JRG), which had been ruling the country since the 1979 Salvadoran coup d'état.

According to United States Marine Corps Colonel Ronald J. Cruz—a former naval attaché to El Salvador—in the first six months of 1980, guerrillas committed around 3,140 acts of violence, including arson, assassinations, and destruction of infrastructure.

[9] On 10 October 1980, five left-wing groups, the Farabundo Martí Popular Liberation Forces (FPL), Communist Party of El Salvador (PCES), National Resistance (RN), People's Revolutionary Army (ERP), and the Revolutionary Party of the Central American Workers (PRTC), joined forces and formed the Farabundo Martí National Liberation Front (FMLN) guerrilla coalition.

[20] As a result, the High Command General Staff, consisting of Colonels Gutiérrez, José Guillermo García, Rafael Flores Lima, and Francisco Adolfo Castillo, placed the military on a "state of alert" in preparation for such an offensive.

[21] In the 1970s, with the rise of left-wing militant groups in El Salvador and after the very brief Football War against Honduras in 1969, the Salvadoran government structured the Army to plan and prepare for counter-insurgency operations.

Weapons supplied by third parties were shipped to Cuba by commercial carriers, then brought clandestinely through the Gulf of Fonseca or overland through Nicaragua.

[25][28][34] The FMLN attacked 43 different locations, including the Ilopango International Airport, the barracks of the 2nd Infantry Division in Santa Ana, and the headquarters of the Treasury Police in San Salvador.

We call on all the people to rise up as a single man, with all means of combat, under the orders of their immediate chiefs, in all war fronts and throughout the national territory.

Revolution or death, we shall win!On 11 January, the High Command General Staff declared a 7 p.m. to 5 a.m. curfew in an effort to curb guerrilla activities.

The Cavalry Regiment under Major Óscar Campos Anaya was deployed from La Libertad to eastern San Salvador to defend the capital from a guerrilla assault that numbered around 500 men.

The FMLN distributed weapons and ammunition to locals, hoping to incite a popular uprising, but the citizenry mostly refused to participate and the poorer citizens barricaded themselves in their homes.

[26][37] Throughout the night of 11 January, the 1st Infantry Brigade continued efforts to expel the FMLN from northern and eastern San Salvador, while the Engineer Instruction Center defended the department of La Paz from a nighttime attack.

[38] Several installations of the National Guard in San Francisco Gotera, Chalatenango, Cinquera, Zacatecoluca, Santa Rosa de Lima, and Suchitoto came under attack early on the morning of 12 January.

Meanwhile, the 3rd Infantry Brigade defended San Francisco Gotera, the capital of Morazán, and the Frontier Detachment 1 was stationed in El Paraíso, Chalatenango, which came under nighttime attacks from the FMLN.

[25][42] FMLN soldiers were optimistic and believed the offensive would succeed as their numbers were similar to those fielded by the Sandinista National Liberation Front (FSLN) in Nicaragua when Anastasio Somoza Debayle was overthrown in 1979.

[44][45] Mena Sandoval ended his mutiny and returned to the 2nd Infantry Brigade, revealing that the FMLN was expecting the arrival of 800 soldiers from Nicaragua.

[41] On 14 January, the United States resumed sending military aid to the JRG, which had been previously ended as a result of the rape and murder of four American missionaries by members of the National Guard in December 1980.

[25] The CDP sought international support and recognition from various political parties and it wanted to pursue dialogue directly with the United States, rather than the JRG.

[26][48] In the second week of the offensive, Robert E. White, the U.S. ambassador to El Salvador, presented evidence that one hundred FMLN fighters had arrived at La Unión on boats from Nicaragua, of which fifty-three had been killed in battle.

[48][57][58][59] They had believed that their actions against the government would spark a "full-scale popular revolution" and that several garrisons would mutiny as had happened in Nicaragua two years earlier.

[57][60][61] Other than the general strike that occurred early in the offensive and the mutiny in Santa Ana, the FMLN did not receive significant support from the citizenry or military.

[26][48] As a result of the offensive, and specifically because of the attack on Ilopango International Airport, Reagan signed an executive order on 1 February 1981 authorizing $55 million in emergency aid and funding for the Salvadoran government.

[59] The FMLN subsequently declared the result of the offensive as a military defeat but a political victory, and later changed its tactics and approaches in combating the government.