Operation Dawn 2

Operation Dawn 2 (also known as Operation Valfajr-2) was an Iranian operation during the eight-year long Iran–Iraq War. This operation opened a new front in northern Iraq/Iraqi Kurdistan also known as "the northern front". Despite Turkish help, this region was Iraq's weak point during the war as the Kurds sided with Iran.

Prelude
In the year leading up to the operation, fighting between Iraqi and Iranian forces drew to a stalemate on the southern front. Iranian forces repeatedly used human wave attacks in the southern marshlands, only to be repulsed by forces of the Iraqi Third Corps. However, the Iranian government managed to win favor of the Kurdish people in parts of northern Iraq, thus allowing the opportunity to take the war north.

The main objective of the mission was the frontier town of Haj Omran, which was nestled on the border and surrounded by a mountainous terrain. Rebels of the Kurdistan Democratic Party of Iraq would prove a great asset to the advancing Iranians, given their knowledge of the terrain and the people.

The battle
On July 22, Iranian forces advanced from Piranshahr and were highly successful against the Iraqis, effectively seizing Haj Omran in the process. The Iranians and Kurdish guerrillas made use of elevated ridges to launch ambushes on Iraqi positions and convoys. In all, they seized roughly 150 sqmi of Iraqi territory.

Iraq responded with counteroffensive, launching an airborne assault and employing the use of poison gas for the first time in the entire war. The Iraqis hit Iranian troops on mountain tops near Haj Omran with mustard gas while their troops advanced in the slopes. The Iraqis were unfamiliar with the properties of poison gas and the agent descended back down to the exposed Iraqi troops. At the same time, the rugged terrain held up Iraqi tanks. The use of helicopter gunships was also hampered, since the Iranian and Kurdish fighters had better cover.

These were the deciding factors that contributed to Iraq's loss of the battle.