Assad's fall followed years of bloodshed and division

The sudden collapse of Bashar al-Assad's rule over Syria marks the culmination of a nearly 14-year rebellion and a key moment in a civil war that killed hundreds of thousands of people, displaced half the population and drew in outside powers.

This is how it unfolded:

2011 - The first protests against Assad quickly spread across the country, and are met by security forces with a wave of arrests and shootings.

Some protesters take up guns and military units defect as the uprising becomes an armed revolt that will gain support from Western and Arab countries and Turkey.

2012 - A bombing in Damascus is the first by al Qaeda's new Syrian affiliate, the Nusra Front, which gains in power and starts crushing groups with a nationalist ideology.

A man gestures at Saadallah al-Jabiri Square as people celebrate, after Syria's army command notified officers on Sunday that President Bashar al-Assad's 24-year authoritarian rule has ended, a Syrian officer who was informed of the move told Reuters, following a rapid rebel offensive that took the world by surprise, in Aleppo, Syria December 8, 2024.Reuters

World powers meet in Geneva and agree on the need for a political transition, but their divisions on how to achieve it will foil years of U.N.-sponsored peace efforts.

Assad turns his air force on opposition strongholds, as rebels gain ground and the war escalates with massacres on both sides.

2013 - Lebanon's Hezbollah helps Assad to victory at Qusayr, halting rebel momentum and showing the Iran-backed group's growing role in the conflict.

Washington has declared chemical weapons use a red line, but a gas attack on rebel-held eastern Ghouta near Damascus kills scores of civilians without triggering a U.S. military response.

Rebel fighters gather in Homs after Syria's army command notified officers on Sunday that President Bashar al-Assad's 24-year authoritarian rule has ended, a Syrian officer who was informed of the move told Reuters, following a rapid rebel offensive that took the world by surprise, in Homs, Syria December 8, 2024.Reuters

2014 - Islamic State group suddenly seizes Raqqa in the northeast and swathes more territory in Syria and Iraq.

Rebels in the Old City of Homs surrender, agreeing to move to an outer suburb - their first big defeat in a major urban area and a precursor to future "evacuation" deals.

Washington builds an anti-Islamic State coalition and starts air strikes, helping Kurdish forces turn the jihadist tide but creating friction with its ally Turkey.

2015 - With better cooperation and more arms from abroad, rebel groups gain more ground and seize northwestern Idlib, but militants are taking a bigger role.

Rebel fighters gather in Homs after Syria's army command notified officers on Sunday that President Bashar al-Assad's 24-year authoritarian rule has ended, a Syrian officer who was informed of the move told Reuters, following a rapid rebel offensive that took the world by surprise, in Homs, Syria December 8, 2024.Reuters

Russia joins the war on Assad's side with air strikes that turn the conflict against the rebels for years to come.

2016 - Alarmed by Kurdish advances on the border, Turkey launches an incursion with allied rebels, making a new zone of Turkish control.

The Syrian army and its allies defeat rebels in Aleppo, seen at the time as Assad's biggest victory of the war.

The Nusra Front splits from al Qaeda and starts trying to present itself in a moderate light, adopting a series of new names and eventually settling on Hayat Tahrir al-Sham (HTS).

Rebel fighters gather in Homs after Syria's army command notified officers on Sunday that President Bashar al-Assad's 24-year authoritarian rule has ended, a Syrian officer who was informed of the move told Reuters, following a rapid rebel offensive that took the world by surprise, in Homs, Syria December 8, 2024.Reuters

2017 - Israel acknowledges air strikes against Hezbollah in Syria, aiming to degrade the growing strength of Iran and its allies.

U.S.-backed, Kurdish-led forces defeat Islamic State in Raqqa. That offensive, and a rival one by the Syrian army, drive the jihadist group from nearly all its land.

2018 - The Syrian army recaptures eastern Ghouta, before quickly retaking the other insurgent enclaves in central Syria, and then the rebels' southern bastion of Deraa.

2019 - Islamic State loses its last scrap of territory in Syria. The U.S. decides to keep some troops in the country to prevent attacks on its Kurdish allies.

People gesture as they hold a flag, after Syrian rebels announced that they have ousted President Bashar al-Assad, in Qamishli, Syria December 8, 2024.Reuters

2020 - Russia backs a government offensive that ends with a ceasefire with Turkey that freezes most front lines. Assad holds most territory and all main cities, appearing deeply entrenched. Rebels hold the northwest. A Turkey-backed force holds a border strip. Kurdish-led forces control the northeast.

2023 - The Hamas attack on Israel on Oct. 7 triggers fighting between Israel and Hezbollah in Lebanon, ultimately reducing the group's presence in Syria and fatally undermining Assad.

2024 - Rebels launch a new assault on Aleppo. With Assad's allies focused elsewhere his army quickly collapses. Eight days after the fall of Aleppo the rebels have taken most major cities and enter Damascus, driving Assad from power.