TIMELINE: The Syria unrest
DAMASCUS, Syria - The British-based Syrian Observatory for Human Rights estimates the total death toll since the start of the revolt at more than 15,800, the majority of them civilians killed by government forces.
These are athe key dates in the 15-month uprising against President Bashar al-Assad's regime in Syria.
15: First protests after Facebook call for a "Day of Dignity."
18-27: Crackdowns in Damascus, Banias and Daraa, cradle of the uprising, where 100 are reportedly killed on the 23rd.
25-26: Protests spread and strengthen, with calls for the regime's fall. In June, the army deploys near the borders with Iraq, Turkey and Lebanon.
15: More than a million people protest, notably in Hama and Deir Ezzor. On the 31st, the army kills 100 in Hama.
18: US President Barack Obama and his allies urge Assad to quit. Western and Arab states later impose sanctions on his regime.
2: Creation of the opposition Syrian National Council (SNC).
16: The Free Syrian Army (FSA), set up in Turkey by a deserter from Assad's army, claims an attack on a Damascus military base.
1: Regime forces seize the central town of Homs' Baba Amr district after a 27-day assault. Rights groups say hundreds killed.
21: The UN Security Council demands that Syria implement a peace plan drawn up by UN-Arab League envoy Kofi Annan, calling for a ceasefire and democratic transition.
12: The UN-backed ceasefire, which the regime accepted, formally begins, but violence continues.
14 and 21: Security Council Resolution 2042 -- the first adopted on the crisis -- calls for unarmed observers to be deployed in Syria. Another resolution authorises the sending of 300 unarmed observers.
25: At least 108 people, including 49 children and 34 women, killed in the central town of Houla in Homs province. Rebels and regime blame each other for the massacre. The Security Council condemns Damascus.
29: 98 people killed across Syria, including 13 "executed" in a new massacre at Assukar in Deir Ezzor province, according to the Syrian Observatory for Human Rights.
6: At least 55 people killed in a new massacre in the central town of Al-Kubeir, the Observatory says. Assad's regime says not responsible.
13: Rebels withdraw from the besieged town of Al-Haffe and nearby villages that had been under intense shelling by regime forces for eight days.
16: The UN observer mission head, General Robert Mood, suspends the work of the observers.
18: Presidents Barack Obama and Vladimir Putin meeting at a G20 summit "call for an immediate cessation of all violence".
19: The UN decides to keep its observers in Syria despite the suspension of their activities.
22: Clashes kill nearly 170 people, mainly civilians, on the deadliest day since the supposed ceasefire came into force, the Observatory says. Meanwhile Syrian government forces shoot down a Turkish warplane near the two countries' border, saying the craft violated their airspace.
26: Fighting between government and armed rebel forces around bases of the Syrian Republican Guard on the outskirts of Damascus.
27: At least 7 staff members of a pro-regime television station near Damascus are killed in a rebel attack on its offices.
30: World powers agree to a plan for a transition in Syria that could include current regime members, but Annan doubts if Syrians would pick leaders "with blood on their hands." - Agence France-Presse