| Conflict: | Siege of Basra Operation Karbala-5 The Great Harvest |
| Partof: | the Iran–Iraq War |
| Date: | 8 January – mid April 1987[1] |
| Place: | Basra Governorate |
| Casus: | Iranian major attempt to capture Basra |
| Territory: | Iran crossed the border and captured a tiny sliver of Basra Governorate[2] |
| Result: | Iraqi victory |
| Combatant1: | Republic of Iraq |
| Commander1: |  Saddam Hussein Gen. al-Rashid[3] Lt. Gen. Dhia ul-Din Jamal[4] Maj. Gen. Khalil al-Dhouri Brig. Gen. Abdul-Wahid Shannan ar-Ribat[5] Brig. Gen. Riyadh Taha Brig. Gen. Hassan Yusuf Brig. Gen. Ibrahim Ismail Brig. Gen. Hamid Salman |
| Commander2: | Akbar Hashemi Rafsanjani[6] Mohsen Rezaee Hossein Kharrazi Col. Ali Sayyad Shirazi Esmail Daghayeghi |
| Units1: | 3rd Corps
6th Corps |
| Units2: | Basij and Revolutionary Guards (70%): Najaf Corps Quds Corps Karbala Corps Nouh CorpsRegular Army (30%) with some artillery and armour |
| Strength1: | 300,000 (four armies) |
| Strength2: | 150,000–200,000 (six divisions from army & rest from the Basij militia) |
| Casualties1: | 10,000 killed 1,750 captured----150 tanks and 10 aircraft lost |
| Casualties2: | 40,000 killed 80,000 wounded----218 armored vehicles 21 boats[8] |
| Casualties3: | ≈2 million civilians displaced |
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. This battle, known for its extensive casualties and ferocious conditions, was the biggest battle of the war and proved to be the last major Iranian offensive. The Iranians failed to reach their objective.[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. They used their bridgehead at Duaiji as a springboard. Between 9–10 January, the Iranians broke through the first and second defense lines of Basra south of the Fish Lake with tanks.[10] [11] The Iranians rapidly reinforced their forces with 60,000 troops and began to clear the remaining Iraqis in the area.[10]
As early as 9 January, the Iraqis began a counter-attack, supported by newer Su-25 and Mig-29 aircraft and by 10 January the Iraqis were throwing every available heavy weapon in a bid to eject the Iranians. Despite being outnumbered 10–1 in the air, Iran's air defenses downed many Iraqi aircraft (45 jets in total), allowing Iran to provide close air support with their smaller air force, which also proved superior in dogfighting. Iraqi tanks floundered in the marshland and were defeated by Cobra helicopters and TOW missile-equipped anti-tank commandos.[10] Though after Januari 13 Iraq was able to fully commit its air power, and this time Iraq did not hold back. Iraqi air force flew over 500 missions in support of Iraqi ground forces on January 14 and 15 alone, and managed to destroy 218Iranian armored vehicles and 21 boats. [12]
Despite superior Iranian infantry tactics, it was the depth of the Iraqi defences, that prevented the Iranians from achieving a victory. In spite of its reinforcements, Iran soon took so many additional casualties that itagain lost forward momentum. By January 16, the U.S. estimated that the fighting had led to roughly 50,000 Iranian and 10,000 Iraqi casualties. The evidence of such casualty levels was all too tangible. Iran suffered an exceptionallyhigh ratio of killed to wounded, and many of the dead were left on the battlefield.
On 19–24 January, Iran launched another infantry offensive, breaking the third line and driving the Iraqis across the Jasim river. The battle became a contest of which side could bring more reinforcements.[11] [10] By 29 January, the Iranians launched a new attack from the west of the Jasim river, breaking through the fourth line. They were within 15km (09miles) of the city. At this point, the battle became a stalemate. Iranian TV broadcast footage of the outskirts of Basra but the Iranians pushed no further.[10] Iranian losses were so severe that Iraq took the offensive and pushed them back, containing the Iranians to the Shalamjah area. The fighting continued and 30,000 Iranians still held positions around Fish Lake. The battle bogged down into a trench war, where neither side could displace the other. Iran attacked several more times but without success. Karbala-5 officially ended by the end of February, but the fighting and siege of Basra continued.
Among those killed was an Iranian commander, Hossein Kharrazi as well as the commander of 9th Division "Badr" Esmail Daghayeghi. Roughly 50,000 Iranians and 10,000 Iraqis became casualties because of Operation Karbala-5. And Iraq's army had taken many material losses.[13] The fighting during this operation was the heaviest and bloodiest during the war, with the area around Shalamcheh becoming known as the "Somme of the Iran-Iraq War".[14] At one point, the situation had so worsened that Saddam ordered several of his officers to be executed. With Iranian aircraft concentrated at Basra, the Iraqis bombed Iranian supply routes with chemical weapons, as well as Iranian cities with conventional bombs, including Tehran, Isfahan and Qom. It is believed that around 3,000 Iranian civilians were killed in these attacks. 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.[15]