[7] Though Iraq ultimately captured the city, it had come at a high cost; the offensive into Khorramshahr, which took 34 days, drew an immense investment of troops, far beyond what Iraqi war plans had envisaged.

The incredible delay allowed Iran to stabilize the frontlines at Dezful, Ahvaz, and Susangerd, consequently enabling the relatively swift mobilization of Iranian reinforcements into oil-rich Khuzestan, which Iraq had sought to annex.

At the time of the Iraqi offensive, Khorramshahr was mainly being defended by the heavily outnumbered Takavaran, some units of the 92nd Armoured Division, the Pasdaran, and local civilian militias.

[8] Iraq's loss of Khorramshahr coincided with a larger Iranian offensive that would mark a turning point in the conflict, as Iran regained nearly all Iraqi-occupied territory and subsequently decided to continue the war with a counterinvasion.

Finally, on September 17, Iraqi president Saddam Hussein declared the 1975 Algiers Agreement null and void, thus setting the countdown to war, which would begin a few days later.

The Dej garrison of the Iranian Army was responsible for much of the city’s outer defences with a single company of British-made Chieftain tanks at their disposal.

While most of these outposts fell to Iraqi mechanized divisions by early morning, September 23, they gave the Iranians enough time to prepare defences in and around the city.

Up until that point, the Iranian forces consisted of the Dej Battalion soldiers, 700 Takavar Marines, 30 Pasdars and Basijis, and 185 personnel from Gendarmerie and Shahrbani.

The sheer weight of the Iraqi tank force was effective against the anti-tank teams, but when Iranian armour was encountered, it stopped attacks cold.

After fierce fighting, the Iraqis briefly occupied the slaughterhouse and the railway station, but were pushed back to previous positions on the outskirts of the city.

On October 14, the Iraqis moved in once again, using the element of night attacks to advance troops, gain surprise, and place observation points in tall buildings.

With these tactics, the Iraqis achieved significant results with Special Forces and Commando units seizing the port and traffic police station.

Armoured brigades seized the Dej barracks in the Taleqani district and gained control of the main highway leading to the Grand Mosque.

[citation needed] The city centre in their sights by October 21, the Iraqis turned their objectives to seizing both the Government building and the bridge linking Khorramshahr to Abadan.

As the fighting moved closer toward the city center, Iranian Chieftains were reduced to a supporting role, since the tanks could not fire as effectively through the tight and narrow streets.

Army and Pasdaran commanders began to issue final evacuation orders with warnings of impending airstrikes by the Iranian Air Force.