On 29 April, Iran launched the offensive. 70,000 Revolutionary Guard and Basij members struck on several axes – Bostan, Susangerd, the west bank of the Karun River, and Ahvaz. The Basij launched human wave attacks, which were followed up by the regular army and Revolutionary Guard support along with tanks and helicopters. Under heavy Iranian pressure, the Iraqi forces retreated. By 12 May, Iran had driven out all Iraqi forces from the Susangerd area. The Iranians captured several thousand Iraqi troops and a large number of tanks. Nevertheless, the Iranians took many losses as well, especially among the Basij.