Al-Rahman Arif is overthrown by the Baathists, led by Hasan al-Bakr and Hussein.

As vice chairman of the Revolutionary Command Council, Saddam Hussein plays a major role in purging the government and military officer corps and replacing the positions with party loyalists.

The new Baath government nationalizes the Iraq Petroleum Company, gaining control of oil fields. Iraq and the Soviet Union agree to a 15-year Treaty of Friendship and Cooperation.

Iraq sends an army to the Syrian front during the Arab-Israeli "Yom Kippur" War.

Kurds and Baathists battle in northern Iraq after a 1970 agreement with Saddam Hussein to give Kurds autonomy is never implemented.

Iraq and Iran sign the Algiers Agreement in which Iran pledges to close its borders to Kurdish immigrants and to cease supporting the Kurdish rebellion in exchange for access to the Shatt al-Arab, a key waterway linking Iraq to the Persian Gulf.

The Revolutionary Command Council and the Baath Party merge, making Baghdad a one-party state.

Saddam succeeds al-Bakr as head of the Baath Party, holding the titles of president of Iraq, secretary general of the party, chairman of the RCC, and commander-in-chief of the Iraqi army. The Shah of Iran is overthrown by Ayatollah Khomeini and tensions between Iran and Iraq re-emerge.

Sept. 4 -- Iran attacks Iraqi towns with artillery shells.

Sept. 17 - Saddam announces on national television the nullification of the 1975 Algiers Agreement.

Sept. 22 -- Iraqi troops invade Iran. The following day, Iran bombs Iraqi military sites.

The U.S. State Department removes Iraq from its list of states supporting international terrorism.

U.S. President Reagan, seeking the blunt the advance of Iran's religious theocracy, sends a special envoy to Iraq, including then-former Secretary of Defense Donald Rumsfeld, to meet with Saddam Hussein.

The United States re-establishes diplomatic ties with Iraq, 17 years after breaking off relations during the Six Day War. Iraq begins using chemical weapons against Iran, as confirmed by a U.N. Security Council resolution issued in 1986.

The Iran-Iraq War becomes a "tanker war" as both countries attack each other's oil frigates in the Persian Gulf.

In March, after Iranians capture the Kurdish town of Halabja, the Iraqi Air Force releases poisoned gas on the town, killing at least 5,000 civilians. The Halabja killings are one of the various incidents later cited in the charge of "crimes against humanity" in the 2006 trial of Saddam Hussein.

In August, a U.N.-brokered cease-fire takes effect. Approximately 262,000 Iranians and 105,000 Iraqis have died in the conflict. Iraq runs up a large debt to other Arab countries.