3rd Corps Basij and Revolutionary Guards (70%):Najaf CorpsQuds CorpsKarbala CorpsNouh Corps 10,000 killed1,750 captured 40,000 killed80,000 wounded[1] Iraqi invasion of Iran (1980) Stalemate (1981) Iranian offensives to free Iranian territory (1981–82) Iranian offensives in Iraq (1982–84) Iranian offensives in Iraq (1985–87) Final stages (1988) Tanker War International incidents The siege of Basra, code-named Operation Karbala-5 (Persian: عملیات کربلای ۵) or The Great Harvest (Arabic: الحصاد الاكبر), was an offensive operation carried out by Iran in an effort to capture the Iraqi port city of Basra in early 1987.

[9] Operation Karbala-5 began midnight 8 January 1987, when a strike force of 35,000 Revolutionary Guards infantrymen crossed Fish Lake, while four Iranian divisions attacked at the southern shore of the lake, overrunning the Iraqi forces and capturing Duaiji, an irrigation canal.

Iraqi tanks floundered in the marshland and were defeated by Cobra helicopters and TOW missile-equipped anti-tank commandos.

[9] On 19–24 January, Iran launched another infantry offensive, breaking the third line and driving the Iraqis across the Jasim river.

Iran retaliated by firing eleven long-range missiles at Iraqi cities, inflicting casualties among civilians and killing at least 300.

The Iraqis had fought an defensive battle at Basra, they had succeeded in fighting the Iranians to a complete standstill thwarting their obsession with capturing the city.

The end of the battle saw a considerable breakdown of Iranian morale as hereafter only a small percent signed up for volunteering in the Revolutionary Guards or Basij.