Siege of Abadan The Siege of Abadan was a major action during the early part of the Iran – Iraq War . Prelude . Abadan island was the site of the Abadan Refinery , one of the worlds largest oil refineries . The plan . In September 1980 Iraqi President Saddam Hussein launched a surprise attack against Iran and invaded Iranian territory on a broad front . Iraq ' s initial plan to attack Abadan Island called for an reinforced armored division to cross the Shatt al - Arab near Kharkiya on the road heading from Baghdad to Basra and then head south to capture the cities of Khorramshahr and Abadan , and subsequently engage any remaining local Iranian units . This reinforced division to be used included 500 - 600 tanks , as well as some special forces units , for a total troop strength of 20 , 000 men . Iraqi commandos , driven by Iraqi initial success in the attack on Khorramshahr , had crossed the Karun River and reached the Abadan city limits on 22 September , but had been forced back by stiff resistance from Iranian paramilitary units , causing the Iraqis to withdraw to the north side of the Karun River , at the cost of several tanks and APCs . By 4 October Iraqi commanders reported that they had secured the main road from Abadan to Ahwaz , however it was not until late November that Iraq fully controlled the bridge to Abadan . As the Iraqi army became preoccupied with the ongoing Battle of Khorramshahr , the original plan was heavily edited , with instead of calling for a quick engagement and occupation of Abadan , the plan now was to isolate local Iranian units within Abadan , and then lay siege to the island . The battle . On November 3 , Iraqi forces reached Abadan in Iran ' s Khuzestan province . Iranian resistance proved too strong , however , so Iraqi commanders called for reinforcements . A second , weakened armored division with a strength of approximately 4 , 500 men and 200 tanks was sent to cut off Abadan and surround the city from the northeast , bypassing Khorramshahr , which was still under siege , by crossing the Karun River to the north of the city . These two Iraqi divisions faced an unknown number of Iranian troops . Most likely sources estimate that a single brigade defended Khorramshahr supported by two operational reserves located further north . The siege . Although the Iraqis were repulsed by the Iranian Pasdaran unit , they managed to surround Abadan on three sides and occupy a portion of the city . However the Iraqis could not overcome the stiff resistance ; sections of the city still under Iranian control were resupplied at night by boat . 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 . Iraqi June Offensive . Facing declining morale and with the Shatt - al - Arab waterway still blocked by the besieged Iranians , Saddam ordered the Iraqis to attack in June , 1981 . The Iranians had reinforced the garrison with 15 , 000 troops , including the Pasdaran , regular army , and Khuzestani Arab fighters . Iraq unleashed an offensive against the city , using 60 , 000 troops and tanks , outnumbering the Iranians 6 - 1 . Despite that , the Iranians defeated the Iraqi assaults . The Iranians used their Chieftain tank s to help defeat the Iraqis . Breaking of the Siege . see : Operation Samen ol - A ' emeh 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 armored vehicles , while losing of their own 150 M - 60 Patton tanks . Aftermath . 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 offensive against Iraq . Eventually , it would result in the driving out of Iraqi troops from Iran and the Liberation of Khorramshahr in 1982 . Bibliography . http : / / books . google . com / books ? id = dUHhTPdJ6yIC & pg = PT835 & lpg = PT835 & dq = Siege + of + Abadan + iran + at + war + 1500 - 1988 & source = bl & ots = LrQ7H19IGb & sig = yWGgtXE6iaBzCjYgduiL _ 38ec3k & hl = en & sa = X & ei = d - 6CUdviEKrr0gG3vIHADw & ved = 0CEQQ6AEwBA