TIMELINE: Events in Iraq since U.S-led invasion

(Reuters) - U.S. combat troops prepared to leave the last of Iraq's cities on Tuesday, a move hailed by Iraqi authorities as restoring sovereignty.

Following is a timeline of key events in Iraq since U.S. and British forces invaded Iraq to topple Saddam Hussein on March 20, 2003:

April 9 - U.S. troops take Baghdad, Saddam disappears.

July 13 - The Iraqi Governing Council -- 25 Iraqis chosen under U.S. supervision -- holds inaugural meeting in Baghdad.

August 19 - Suicide truck bomb at U.N. headquarters in Baghdad kills 22 people, including U.N. envoy Sergio Vieira de Mello.

August 29 - A car bomb kills at least 83 people, including top Shi'ite Muslim leader Ayatollah Mohammed Baqer al-Hakim, at the Imam Ali mosque in Najaf.

December 13 - U.S. troops capture Saddam near Tikrit. U.S. governor of Iraq Paul Bremer breaks news with: "We got him."

March 2, 2004 - Bombers killed 171 people in Baghdad and the Shi'ite holy city of Kerbala. The coordinated attacks came as majority Shi'ites marked Ashura, one of their holiest days, for the first time since the overthrow of Saddam Hussein.

March 8, 2004 - Governing Council signs interim constitution.

June 1 - Governing Council dissolved to make way for interim government led by Iyad Allawi. Ghazi al-Yawar named president.

June 28 - United States formally returns sovereignty. Coalition Provisional Authority dissolved. Bremer leaves Iraq.

January 30, 2005 - Shi'ite-led United Alliance dominates vote for local councils and interim parliament.

March 16 - National Assembly holds first meeting.

October 15 - Referendum ratifies constitution by 78 percent despite Sunni Arab opposition which nearly vetoes it.

October 19 - Saddam goes on trial charged with crimes against humanity for the killing of 148 Shi'ite men and boys in Dujail after a 1982 assassination attempt. He pleads not guilty.

December 15 - Parliamentary election. Sunnis vote in strength.