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. The 2nd Infantry Brigade began efforts to reclaim Santa Ana where the FMLN raised their banner, signifying the fall of the city to their forces, and around 85% of the city was recaptured by the end of the day. The 2nd Infantry Brigade also secured Metapán and prevented it from surrendering to FMLN forces. Soldiers from the Recruit Instruction Center and the Artillery Brigade were dispatched to support the 2nd Infantry Brigade. 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 attack from nighttime attacks from the FMLN. By the end of the day, the FMLN captured and secured Mendez Island near El Triunfo in Usulután. The Guatemalan Army was mobilized on the Guatemalan–Salvadoran border to prevent any soldiers of the FMLN from entering the country, which itself was in the midst of its own civil war.