|Part of Iran-Iraq War|
<th colspan="2" style="background-color: #B0C4DE; text-align: center; vertical-align: middle;">Belligerents</th>
<td style="width:50%; border-right:1px dotted #aaa;"> Iraq
</td><td style="width:50%; padding-left:0.25em"> Iran
<th colspan="2" style="background-color: #B0C4DE; text-align: center; vertical-align: middle;">Commanders and leaders</th>
<td style="width:50%; border-right:1px dotted #aaa;"> Saddam Hussein
Operation Karbala-5 was an offensive 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 beginning of the end of the Iran-Iraq War.
With the Iran-Iraq War in its seventh year, both sides were determined to break the stalemate. Iran’s target was the city of Basra, which was both a key port and vital oil source for Iraq. Iran decided that the city had to fall in order for Saddam Hussein to fall as well. Iran had besieged the city since 1982, yet it remained determined to make this the ‘final battle’ of the war. The Iranians also wanted to link up with forces in the already captured Fao Peninsula in southern Iraq. The timing of the operation was to coincide with winter, so that the heavy rains would hinder the Iraqi armor and air defenses. The Iraqis, however, intended to break the stalemate by inflicting as many casualties as possible on the Iranian forces, hoping to break the morale of the Iranian people.
Making up the manpower of the Iraqi army were six conscript brigades as well as two brigades of the elite Republican Guard nearby. The Iraqis set up an artificial barrier facing Iran, using dykes and the man-made Jasim river leading from the Shatt al Arab to create an artificial lake. Known simply as ‘Fish Lake,’ the man-made barrier was approximately 30 kilometers long and 1,800 meters wide. Soldiers described a smell of 'dead fish' since so many shells rained down on the lake. Iraqi engineers even managed to place electrodes in the waters. Furthermore, the Iraqis set up mine fields, a series of trenches, concrete bunkers, and barbed wire, totaling five lines of defense. In addition, behind each waterway and defensive line was radar-guided artillery, ground attack aircraft, and combat helicopters; all capable of firing poison gas in addition to conventional munitions. By the time the defenses were complete, the Iraqis came to know the entire barrier as the 'wall of steel.'
Iran's strategy was to penetrate through these massive defensive lines, and encircle Basra, cutting off the city as well as the Al-Faw peninsula from the rest of Iraq. While being the largest and most sophisticated attack since 1984, it was actually a part of Iran's attritional stategy, in order to strike an unsustainable blow against Iraq, as the Iranians had little hope of a decisive victory in the face of Iraq's massive rearmament. There were hopes that it could bring about Iraq's downfall through sheer depletion and/or make Basra an alternative pro-Iran capital for a new Iraqi government.  Iran's plan was for a diversionary attack near Basra, the main offensive, and another diversionary attack using Iranian armor in the north to have Iraqi heavy armor diverted away from Basra. For these battles, Iran had re-expanded their military by recruiting many new Basij and Pasdaran volunteers. 
The Iranians amassed over 650,000 Pasdaran and Basij fighters of the ‘Muhammad Corps.’ The Corps itself consisted of men, with even a few between the ages of seventy all the way down to twelve. The Corps did not have as extensive training as their Iraqi counterparts did, having received from forty days of training to none at all. The Iranians did however enjoyed the luxury of large scale helicopter-borne support, which included the use of Bell and Chinook helicopters. Ali Akbar Hashemi Rafsanjani praised the troops heading for the front before the operation commenced:
Our aim is to completely destroy the Iraqi war machine. Here, near Basra, Saddam can not do anything but fight, for the fall of Basra is tantamount to his own death. We want to settle our accounts with Iraq at Basra's gates, which will open and pave the way for the final victory we have promised.
On Christmas Eve of 1986, Iran launched the Operation Karbala-4 under cover of dark. The battle was short lived, however, as the Iraqi defenses pummeled the Iranian forces coming ashore. Though a failure, Iran continued with further operations and mobilized the Pasdaran's most experienced officers for battle. After two weeks, Iran officially launched Operation Karbala 5.
Under the code words ya Zahra (یا زهرا , "Zahra help us"), Operation Karbala 5 began midnight 9 January with the Revolutionary Guard and Basijis attacking the Iraqi defence south of Fish Lake and overrunning a battalion of Iraqi infantry. Another wave of Iranians crossed the lake by boat and landed on the western shores, where they charged towards the Shatt al-Arab river. Instead, they faced a counter-attack by Iraqi Republican Guard brigades, resulting in heavy casualties on both sides. After the southern thrust captured the poorly-defended town of Ad Duayji, Iraq, the Iranians spent 9 and 10 January overrunning two of the five Iraqi defence lines, reportedly using dug-in Iraqi tank turrets to shell Basra and other fortifications, along with their own tanks as well.  
On 14 January, Iraqi Border Guards found themselves nearly cut off in the third line of trenches by Iranian forces moving in on both flanks. Air and artillery attacks dampened, as the marshes absorbed the impact of shells and rockets. After fierce fighting, they withdrew across the Jasim River on 17 January, and the Iranians charged south towards the Shatt al-Arab, taking a small island in the Shatt. However, the Iraqis managed to repulse the capture of the island by moving in from the south on land. In the following days, the Iranians managed to secure a bridgehead along the shorelines, 9.5 km (5.9 mi) into Iraq. The Iraqis later admitted that they lost 50–60 jets to Iranian surface-to-air missiles (10% of their air force) and fighter jets and for a brief period the Iranians gained air superiority with their limited air power, allowing both fighter jets and helicopters to attack tanks and other ground targets. Iran had also managed to secretly import Swedish RBS 70 shoulder-fired MANPADS.
The smaller Iranian air force dominated in dogfights, and with their stronger air defense, they deterred and caused the much larger Iraqi air force to stop temporarily providing close air support for their troops. Instead, the Iraqis began bombing 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 further into Iraqi territory, continually inflicting heavy casualties among civilians and killing at least 300. Later in the battle, after their ground forces taking heavy losses due to the lack of air support, the Iraqi aircraft came back to the battlefield once again, facing their Iranian counterparts.
By 22 January, the Iranians launched a new attack, breaking through the fourth of the five defense lines. They were within 12 km (7.5 mi) from the city. At this point, the battle became a stalemate. The Iraqis found themselves on the outer perimeters of Basra, whereas the Iranians were close enough to see the eastern buildings of the city. Iranian TV broadcast footage of the outskirts of Basra, but the Iranians could move no further. Artillery and medium-range missiles created frequent and heavy bombardments, and Iraqi forces had to evacuate much of the civilian population into the northern Iraq.
The situation had deteriorated to the point that Saddam Hussein made a rare visit to the troops. During his visit, Saddam announced a significant shake-up of the chain of command, relieving Major General Khalil al-Dhouri of the 3rd Corp of his post and executing several lower-ranking officers by firing squad due to their poor performance. Khalil al-Dhouri was replaced with Lieutenant General Dhia ul-Din Jamal of the 5th Corps from northern Iraq. Iraq even resorted to trying to recruit children as young as 15 to increase their manpower (despite decrying similar Iranian actions earlier).  Iran's Speaker of Parliament and Commander in Chief of the Armed Forces Ali Akbar Hashemi Rafsanjani was also visible on the war front, reportedly observing the gains made by Iranian forces.
By the fourth week of the offensive, Iran effectively held Fish Lake, the Umm al-Tawil islands, the Jasim River, and Duayji. However, the majority of Iranian forces were spent. Iraqi artillery and mortar fire zeroed in on Iranian re-supply routes, hindering advancing forces with both conventional and chemical weapons while the Iranians took refuge in dugouts.
The Iraqi Republican Guard launched a counter-attack on 28 January. Using waves of tanks, artillery, and helicopter gunships, the Iraqi Third Army Corps assaulted the Iranians on the western side of Fish Lake before turning south towards Jasim. Artillery effectively pounded Iranian re-supply and reinforcement routes. These bombardments, along with the advancing Iraqi armour into the battle zone, created a pincer movement that crushed the salient by 7 February.
Among those killed was Iranian commander Hossein Kharrazi. The Iranians came close to breaking through the Iraqi lines and taking Basra, but in the end, the strength of the Iraqi lines again halted the Iranian offensive.:263 However, the Iranians came close enough to Basra to bring up their artillery, and in the ensuing bombardments, the city was largely destroyed.:263 Despite their losses, the Iranian high command issued a statement, claiming capture of 155 km2 (60 sq mi) of enemy-occupied territory and the Iranian town of Shalamcheh; the destruction of 81 Iraqi brigades and battalions; the destruction of 700 tanks and 1,500 other vehicles; the downing of 80 Iraqi warplanes; the destruction of 250 anti-aircraft guns and 400 pieces of military hardware; the capture of 220 tanks and armoured personnel carriers; and 40,000 enemy dead. The Iraqis claimed 65,000 Iranians were killed during the battle.
Iran continued its shelling of Basra for the remainder of February, at one point setting fire to a petrochemical plant which released toxic gas south of the city. But it was clear by the end of the month that Iran had officially aborted the operation.
It was reported by March that the Iraqis lost 20,000 troops and 45 aircraft, while the Iranians lost 65,000 troops. Of the most experienced Pasdaran recruited to lead the campaign, roughly a quarter of them were killed. Basra’s former population of one million decreased to 100,000, the refugees having fled north to Baghdad. Nearly every building along the eastern end of the city was damaged or destroyed.
Despite the fact the battle was considered to be over, it would remain in a quasi-siege until Operation Tawakalna ala Allah launched by Iraq in April 1988. The Iranians would bombard the city, while the Iraqis would sit behind their defensive lines. With the exception of Operation Karbala-8 launched against the city in July 1987, the Iranians would launch no more large scale attacks against Basra (or anywhere else in Iraq for that matter).
After Operation Karbala-5, the Iranian military was effectively a weakened force, and did not launch large-scale offensives for the rest of the war. Much of the experienced Pasdaran were killed during the battles, in addition to Iranian morale being scarred. The head of the armed forces Hashemi Rafsanjani announced during a news conference to finally end the use of human wave attacks. Mohsen Rezaee, head of the Pasdaran (IRGC), announced that Iran would focus exlusively on limited attacks/infiltrations, while arming and supporting opposition groups inside of Iraq (such as the Kurdish guerillas and Badr Brigade).  While Iraq would be unable to truly defeat Iran and remained on the defensive until 1988, this loss, coupled with earlier ones and Iraq's 1988 offensives depleted Iran's manpower and economy, and convinced their leadership that the war was unwinnable, and accept the UN Resolution 598 ceasefire.
Though the Iraqis forced the Iranian offensive back, it was still an embarrassment due to the fact that Iran came so close to the gates of Basra, and they themselves had taken severe losses. At one point, Saddam Hussein nearly faced mutiny from his generals, who demanded the freedom to conduct operations without political interference. The battle also served as a lesson for Western forces during Operation Desert Storm. With the failure of the poorly trained and equipped Iraqi Popular Army during the first assaults of the offensive, the Republican Guard did the most in repulsing the Iranians. This show of favoritism in Saddam's army would only prove futile in the future.
The effects of the operation were also felt in the Persian Gulf, with Iran and Iraq attacking foreign oil tankers doing business with both powers. A total of sixteen ships were hit in the first five weeks of 1987. Although Iran boasted that it would step up more attacks in the next year, no such actions materialized and Karbala 5 proved to be the last in a series of 'final offensives.' The war ended on August 20, 1988.
1. The Great War for Civilisation: the Conquest of the Middle East, by Robert Fisk, Knopf Books, 2005
2. The Gulf Iran Strikes on Two Fronts, by William E. Smith, TIME Magazine, Jan. 26, 1987
3. The Gulf, TIME Magazine, Feb. 2, 1987
4. The Gulf Life Among Smoldering Ruins, by Dean Fischer, TIME Magazine, March 30, 1987
5. In The Name of God: The Khomeini Decade, by Robin Wright, Simon and Schuster, 1989
6. Essential Histories: The Iran Iraq War 1980-1988, by Efraim Karsh, Osprey Publishing, 2002
7. Journey to Heading 270 Degrees, by Ahmad Dihqan and Paul Sprachman, Mazda Publishers, 2006
8. The Longest War, by Dilip Hiro, Routlage Chapman & Hall, 1991.
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