Honduras had set up logistics lines for its rapidly advancing army, Honduras wanted La Union to cripple the Salvadoran navy in the Gulf of Fonseca and use the city as a staging base for the rest of the operation. El Salvador had decided to call up anything they could spare but was only 700 Salvadoran troops but were well trained conpaired to the 6 460 Honduran troops that were mainly conscripts.
At 9:00 PM Salvadoran Time, the Honduran artillery opens fire on La Union, destroying or heavily damaging the large buildings of the city. One Salvadoran officer described how the night barrage was for him saying "The sky lit up brighter than a night full of stars and while keeping my position I swear I heard so many people screaming even though it was miles away.". The Hondurans had brought 12 their 20 locally produced M4 Sherman medium tanks and 4 of their 8 locally produced 4 2S3 Akatsiya Self-Propelled Howitzer, Even though Honduras had 12 M4 Shermans but were used as mobile artillery.
On February the 19th, a Salvadoran Strela-2 missile shot down a Honduran A-37 Dragonfly light attack jet that was on a reconnaissance mission over the city.
February 20th The Salvadoran Army with 2 A-37 Dragonfly light attack jets flying from San Salvador started a 16 hour house to house and street to street fighting that started at 5:00 AM and were able to take back the last suburbs. The Honduran Army, demoralized from the Salvadoran counter-attack on their positions, retreated in confusion.
When the Hondurans were flushed out of the city, the Salvadoran Army's morale went up and started chasing the disorganized Honduran Military units. Most historians believe that if Honduras used its naval assets, they would have been able to secure La Union.