Nevertheless, with Iranian support, the Iraqi attempts were unsuccessful, and were a major headache for Saddam and his deputies. The Iranians struck south-east of Sulaymaniyah where they easily defeated most of the Iraqi defenders because Saddam Hussein left them to defend even the most exposed positions. After the Iranians had defeated the Iraqi forces at the front lines, they advanced quickly. However, the Iraqis launched a counter-attack during the Iranian advance. The Iraqi soldiers involved in the counter-attack were ambushed by the Iranians and most Iraqi troops were killed. Victory seemed to be in the hands of Iranians as they came close to Sulaymaniyah but they failed to capture it. The Iranians also came dangerously close to Iraq's Darbandikhan reservoir. The Iraqis responded by launching 720 chemical artillery rockets and 200 chemical artillery shells which resulted in the Iranian 55th parachute division taking heavy losses and wiping out of the 84th infantry division, forcing the Iranians to call off the offensive. The Iraqi counter-attack was a disaster for the Kurds. Saddam responded with a chemical gas attack on Halabja. The Halabja poison gas attack occurred in the period 15–19 March 1988 during the Iran–Iraq War when chemical weapons were used by the Iraqi government forces on the Iraqi Kurdish town of Halabja (population 80,000). This was separate from the al-Anfal Campaign but both were considered acts of genocide. Halabja, which is located approximately 150 miles northeast of Baghdad and 8–10 miles from the Iranian border, was significantly damaged with casualties estimated to be around 5,000.