they did not have any tear gas. The United States had never provided them with this item.
Combined with the failure of the other guerrilla efforts throughout San Salvador, the guerrillas had only one way out and took it, starting a headlong withdrawal toward the Guazapa volcano. The armed forces pursued by maintaining pressure on the ground and by airlifting forces in behind the withdrawing guerrillas to act as stop groups. The pressure was such that the guerrillas were not able to reorganize their forces, or even to evacuate their wounded. For the Parachute Group, the Belloso Battalion, and the Special Operations Forces Group, this pursuit lasted for 40 kilometers and eleven straight days of uninterrupted combat.
The main failure of the FMLN was its evaluation that the civilian population in El Salvador was ready for insurrection. The people did not accept the weapons from the FMLN and did not support the offensive. When they had the chance, they fled from the guerrilla-occupied neighborhoods over to government lines. The bulk of civilian support was for the government troops, and without it the FMLN would probably have been victorious.
A second serious failure of the FMLN was to underestimate the ability of the armed forces to adjust to combat in urban terrain. The armed forces did suffer heavy initial casualties, but they learned quickly. The FMLN particularly underestimated the ability of the cavalry's armored cars and the air force's helicopters and gunships to operate against guerrilla positions in fortified urban centers.
Finally, the FMLN's failure to maintain serious reserve forces that could be used to change or modify the battle's center of gravity meant that, except for during the first day or two of the offensive, the military initiative was almost entirely in the hands of the armed forces.