Iran–Iraq War
Battle of the Marshes

By 1984, the Iranian ground forces were reorganised well enough for the Revolutionary Guard to start Operation Kheibar, which lasted from 24 February to 19 March. On 15 February 1984, the Iranians began launching attacks against the central section of the front, where the Second Iraqi Army Corps was deployed: 250,000 Iraqis faced 250,000 Iranians. The goal of this new major offensive was the capture of Basra-Baghdad Highway, cutting off Basra from Baghdad and setting the stage for an eventual attack upon the city. The Iraqi high command had assumed that the marshlands above Basra were natural barriers to attack, and had not reinforced them. The marshes negated Iraqi advantage in armor, and absorbed artillery rounds and bombs. Prior to the attack, Iranian commandos on helicopters had landed behind Iraqi lines and destroyed Iraqi artillery. Iran launched two preliminary attacks prior to the main offensive, Operation Dawn 5 and Dawn 6.

Operation Kheibar began on 24 February with Iranian infantrymen crossing the Hawizeh Marshes using motorboats and transport helicopters in an amphibious assault. The Iranians attacked the vital oil-producing Majnoon Island by landing troops via helicopters onto the islands and severing the communication lines between Amareh and Basra. They then continued the attack towards Qurna. By 27 February, they had captured the island, but suffered catastrophic helicopter losses to the IrAF. On that day, a massive array of Iranian helicopters transporting Pasdaran troops were intercepted by Iraqi combat aircraft (MiGs, Mirages and Sukhois). In what was essentially an aerial slaughter, Iraqi jets shot down 49 of the 50 Iranian helicopters. At times, fighting took place in waters over 2 m (6.6 ft) deep. Iraq ran live electrical cables through the water, electrocuting numerous Iranian troops and then displaying their corpses on state television.

By 29 February, the Iranians had reached the outskirts of Qurna and were closing in on the Baghdad–Basra highway. They had broken out of the marshes and returned to open terrain, where they were confronted by Iraqi artillery, tanks, air power, and mustard gas. 1,200 Iranian soldiers were killed in the counter-attack. The Iranians retreated back to the marshes, though they still held onto them along with Majnoon Island.

The Battle of the Marshes saw an Iraqi defence that had been under continuous strain since 15 February. They were relieved by their use of chemical weapons and defence-in-depth, where they layered defensive lines: even if the Iranians broke through the first line, they were usually unable to break through the second due to exhaustion and heavy losses. They largely relied on Mi-24 Hind to "hunt" the Iranian troops in the marshes. At least 20,000 Iranians were killed in the marsh battles. Iran used the marshes as a springboard for future attacks/infiltrations.

Four years into the war, the human cost to Iran had been 170,000 combat fatalities and 340,000 wounded. Iraqi combat fatalities were estimated at 80,000 with 150,000 wounded.
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