BEIRUT (Reuters) - Syria marks the ninth anniversary on March 15 of the start of its conflict.
A Russian-backed government offensive to recapture Idlib province from rebels has been underway since December and has caused the biggest flight of civilians of the war.
This timeline shows how it began with peaceful pro-democracy protests against President Bashar al-Assad then developed into a multi-sided conflict that has pulled in world powers, killed hundreds of thousands of people and made millions refugees.
* March 2011 - The first protests against Assad’s authoritarian family rule spread across the country, security forces respond with arrests and shootings.
* June 2012 - World powers meet in Geneva and agree on the need for a political transition, but divisions on how to achieve it will foil years of U.N.-sponsored peace efforts.
* July 2012 - Assad launches air raids on towns and cities that had rebelled against his rule, as once peaceful protesters now carry arms. Thousands are killed.
* Aug. 2013 - Washington has declared the use of chemical weapons a red line, but a gas attack on rebel-held eastern Ghouta kills hundreds of civilians without triggering a U.S. military response.
* Jan. 2014 - An al-Qaeda splinter group seizes Raqqa before grabbing territory across Syria and Iraq, declaring a caliphate and renaming itself Islamic State.
* Sept. 2014 - Washington builds an anti-Islamic State coalition and starts air strikes, helping Kurdish forces turn the jihadist tide but creating friction with ally Turkey.
* March 2015 - As Assad’s forces lose ground in many areas, rebel groups gain more and seize northwestern Idlib city, but Islamist militants are taking a bigger role.
* Sept. 2015 - Russia joins the war on Assad’s side, deploying warplanes and giving military aid that soon turns with the help of Iran the course of conflict against the rebels.
* Aug. 2016 - Alarmed by Kurdish advances on the border, Tureky launches an incursion with allied rebels, making a zone of Turkish control that it later extends in 2018.
* Dec. 2016 - The Syrian army and its allies defeat rebels in their biggest urban base of Aleppo after months of siege and bombardment, confirming Assad’s momentum.
* March 2017 - Israel acknowledges making air strikes against Hezbollah in Syria, aiming to degrade the strength of Iran and its allies who expand their influence in Syria.
* April 2017 - The United States launches a first cruise missile attack on a Syrian government airbase near Homs after a poison gas attack on rebel-held Khan Sheikhoun.
* Nov. 2017 - U.S.-backed, Kurdish-led forces defeat Islamic State in Raqqa. That offensive, and a rival one by the Syrian army, drives the jihadists from nearly all their land.
* April 2018 - After months of blockade and air raids, the Russian-backed army recaptures eastern Ghouta, before retaking the other insurgent enclaves in central Syria, and then the rebels’ southern bastion of Deraa in June.
* Sept. 2018 - A Russian-Turkish deal over Idlib and the rebel-held northwest freezes the frontlines and reduces the bombing raids that killed hundreds of civilians in the last major opposition bastion.
* March 2019 - As its local allies take Islamic State’s last area in the east, the United States decides to keep some troops in Syria after earlier saying it would pull out.
* April-Dec. 2019 - Russian-backed forces launch a campaign in the northwest that ends after months of bombing and the capture of Khan Sheikhoun in August.
* A Russian-Turkish summit in October reduces fighting until Moscow resumes the assault in December and pushes with its allies deeper into the last opposition bastion.
* Dec. 2019 - March 2020 - The government retakes several areas in the northwest, prompting Ankara to launch a counter-offensive and open its borders. Thousands flee for Greece.
* March 2020 - Turkey and Russia agree a ceasefire for Idlib, vowing to hold joint patrols and establish a secure corridor near the M4 highway.
Reporting by Beirut newsroom; Editing by Angus MacSwan