The fourth major confrontation began at 6 am, Wednesday, and continued in several stages until Thursday afternoon. The regime's agents had been reinforced, and new forces - the 71st Ruhollah division, the 61st Moharram artillery brigade, and the 155th special brigade - had been dispatched to capture the southern heights and, from there, retake the town via Sugar Factory road.
The NLA brigades had repelled the enemy's last attack only hours ago, and were in control of Islamabad's southern section.
According to plan, all the town's entrances and exits as well as its strategic points, like the Sugar Factory near the southern entrance, were under tight control. Before launching its attack, Khomeini's Guards Corps sent some Jondollah intelligence agents, posing as deserters, into Islamabad to gather information for their assault. Some of these agents were arrested by the NLA combatants and revealed their mission.
By 6 am, the enemy had concentrated its forces in the orchards and farms south of the town. Khomeini's Guards launched their attack and clashes continued until late that night. The NLA combatants immediately launched a counter- attack. With three infantry and one armored column, they pounded the enemy forces. The NLA then took the southern heights overlooking 11am road as planned, and cleared them of enemy agents. At this point, the enemy sent massive reinforcements to circumvent the heights. But an NLA column opened fire and routed all of them. The Guards hidden in the ridges were cut off by the lightning NLA attack.