TIMELINE: Iraq from invasion to pact

(Reuters) - Following is a chronology of key events in Iraq since the U.S.-led invasion in 2003 that toppled Saddam Hussein.

March 20, 2003 - U.S. and British forces invade from Kuwait.

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 wrecks U.N. headquarters in Baghdad, killing 22 people, including U.N. envoy Sergio Vieira de Mello.

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

March 8, 2004 - Iraq 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 election for interim parliament. Most Sunnis don't vote.

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.

February 10, 2006 - Final results give Shi'ite Alliance near majority with 128 seats. Sunnis have 58 and Kurds 53.

February 22 - Destruction of Shi'ite shrine in Samarra sparks widespread sectarian violence, raising fears of civil war.