Operation Valfajr-4 ( Dawn 4) was an Iranian operation of the Iran-Iraq War launched in 1983. At the end of the operation Iran had captured important territory from the Iraqis.
The offensive came on 19 October 1983 as the Iranians and guerillas of the Patriotic Union of Kurdistan took 250 square miles (650 km) of territory. This included a number of Kurdish villages and exerted a significant amount of pressure on Penjwin.
Saddam Hussein responded with a counterattack, using the Iraqi Republican Guard and poison gas. However, they failed to dislodge the Iranians, who were dug-in and reinforced by Kurdish fighters.
The attack was very successful but the Iranians suffered high casualties due to unjustified and illegal Iraqi gas attacks. Iran gained 110 km2 (42 sq mi) of its territory back in the north, gained 15 km2 (5.8 sq mi) of Iraqi land, and captured 1,800 Iraqi prisoners while Iraq abandoned large quantities of valuable weapons and war materiel in the field.Unlike other operations and battles of the Iran–Iraq War, environmental conditions and operative restrictions were of high significance for this operation. Also the military medicine organization of the Pasdaran was important in this battle; they used special methods to save the wounded and carried out rescue operations.