In 1973-74, negotiations with al-Barzani and the Kurdish Democratic Party
(KDP) to implement the March Manifesto failed. The census promised in the March Manifesto had not been taken, and
al-Barzani and the KDP refused to accept the Ba'thist determination of the borders of the Kurdish area, which excluded the oil-rich Kirkuk province. Nevertheless, on March 11, 1974, the Ba'th regime proceeded to implement its own plan for self-rule, establishing a provincial council and an assembly in cooperation with Kurdish leaders who were opposed to
al-Barzani's militant approach.
The Kurdish war started in March 1974. Al-Barzani's decision to go to war with the Ba'th government seems to have been made with the support of the shah of Iran, who sought to pressure Iraq to alter the water frontier in the Shatt al-'Arab to the
thalweg, or median line of the river. (Under the terms of the 1937 treaty, the boundary was set at the low-water mark on the Iranian side, giving Iraq control of the shipping channel.) The shah stopped his assistance to
al-Barzani when the Ba'th regime agreed to negotiate with him about the Shatt al-'Arab boundary.
The shah and Saddam Hussein met in Algiers in March 1975, and they came to an agreement quickly. Saddam Hussein agreed that the thalweg would be the boundary in the Shatt al-'Arab, and the shah promised to stop his assistance to the Kurds. On the basis of the Algiers Agreement, the foreign ministers of Iraq and Iran met in Baghdad on June 13, 1975, and signed an elaborate treaty embodying the settlement of all disputes relating to frontiers between the two countries. This agreement virtually ended the Kurdish war.
After 10 years of intermittent fighting, a cease-fire agreement was reached followed by a general amnesty for the insurgent Kurds, and in 1974 a law defining the Kurdish autonomous region was promulgated by Iraq. Barzani found this compromise unacceptable and ordered his Pesh Merga ("Forward to Death") Kurdish forces to resume fighting, this time with considerable support from Iran. When Iranian support ended in 1975, the Kurdish guerrillas were overrun by the Iraqi forces.