However the Iraqis could not overcome the stiff resistance; sections of the city still under Iranian control were re-supplied, and received re-inforcements to replace losses, at night by boat and by helicopter. The Iraqis kept up a siege for several months, but never succeeded in capturing Abadan. Much of the city, including the oil refinery, was badly damaged or destroyed by the siege and by bombing. Facing declining morale and with the Shatt-al-Arab waterway still blocked by the besieged Iranians, Saddam ordered the Iraqi troops to attack in June, 1981. The Iranians had reinforced the garrison with 15,000 troops, including the Pasdaran, regular army, and local Khuzestani Arab fighters. Iraq unleashed an offensive against the city, using 60,000 troops and hundreds of tanks, outnumbering the Iranians 4–1. Despite that, the Iranians defeated the Iraqi assaults. The Iranians used their Chieftain tanks to help defeat the Iraqis. From 22–27 September 1981, Iran carried out Operation Samen-ol-A'emeh. During this battle, Iran carried out the first major use of human wave attacks. The siege of Abadan was broken, Iran took 3,000 casualties while the Iraqis took half of that number. Iran captured 2,500 prisoners and destroyed hundreds of armored vehicles, while losing of their own 170 M-47, M-48, M-60 Patton tanks and Chieftain tanks. On 15 October, the Iraqis forced their way to within of Abadan and captured the city's radio-television station. In a separate engagement farther north, near the Iraqi blocking position near Dar Khuyeh, an Iraqi armor force ambushed a large Iranian convoy, escorted by tanks coming from Ahwaz. Apparently this Iranian force was attempting to carry supplies to the besieged defenders of Abadan by way of the Abadan-Ahwaz highway. The short, but intense battle matched Iraqi T-55 and T-62 tanks against Iran's Chieftains. This skirmish, which appears to have involved about a battalion's worth of combat vehicles from each side, was an Iraqi victory as "the Iranians abandoned at least 20 Chieftains and other armored vehicles, and decamped on foot." Abadan was largely in ruins in the aftermath of the siege. The Iraqi threat to Abadan had been broken, and the Iranians had managed to launch their first successful counteroffensive against Iraq. Eventually, it would result in the driving out of Iraqi troops from Iran and the Liberation of Khorramshahr in 1982.