More than 162,000 deaths, millions displaced and a country in ruins.
Here are the key dates marking how a brutally repressed revolt against Syrian President Bashar al-Assad's rule has degenerated into a civil war during the past three years.
-- March 15-16: Demonstrations held in Damascus for "a Syria without tyranny". Authorities clamp down on rallies in Damascus and Daraa to its south, slamming an "armed rebellion of Salafist groups".
-- March 23: Some 100 people reportedly killed in a crackdown in Daraa, cradle of the uprising. Protests spread across Syria from April with calls for Assad's overthrow.
-- July 30: An army colonel who defected from the military announces the formation of the Free Syrian Army. At its birth, the FSA is mainly composed of army defectors. Later, civilian volunteers form the majority of its fighters.
-- August 18: US President Barack Obama urges Assad to quit. Western and Arab governments later impose sanctions.
-- October 4: China and Russia veto a UN resolution condemning the government crackdown on protests. Two more aborted resolutions follow in 2012.
-- March 1: The Syrian army regains control of Baba Amr, a rebel bastion in the central city of Homs, after a month of shelling that a non-governmental organisation says killed hundreds, including journalists Marie Colvin and Remi Ochlik.
-- June 30: Major powers reach an agreement in Geneva on a political transition that does not spell out Assad's future. The accord is never implemented.
-- July 18: Bombing in Damascus kills four top security officials, including Assad's brother-in-law Assef Shawkat. Two days later the FSA launches an offensive in which it seizes swathes of Aleppo, the main northern city.
The army hits back in August with heavy weapons, including warplanes.
-- November 11: Opposition groups sign a unity deal in Doha and form the Syrian National Coalition.
-- February 14: Iran's Revolutionary Guards say a senior officer has been killed by Syrian rebels, having previously acknowledged some of its military "advisers" were inside Syria.
-- June 5: The Syrian army and fighters from Lebanese Shiite movement Hezbollah recapture Qusayr, a strategic town near the Lebanese border.
Inter-confessional strife increases, pitting Shiite Muslims loyal to Assad's Alawite regime against majority Sunni Muslims.
-- August 21: A sarin gas attack in the Damascus suburbs sparks international outrage. Hundreds are killed and in September, a Russian-US deal to dismantle Syria's chemical arsenal averts threatened US military action.
-- January 3: Rebel groups launch an offensive against their erstwhile allies in the Islamic State of Iraq and the Levant, accusing the jihadist group of widespread abuses.
-- January 22: Talks begin in Geneva between Syrian regime and opposition delegates at the behest of US and Russia, but end without a breakthrough.
UN mediator Lakhdar Brahimi indefinitely adjourns them on February 15.
-- May 9: The Syrian army enters Homs's Old City neighbourhood, which has been under siege for nearly two years, after 2,000 rebel fighters withdraw under an unprecedented agreement with the government.
-- May 22: Regime forces break a year-long siege of the central prison in Aleppo, cutting off a major rebel supply route.