Turkish-backed rebels captured the emblematic northern Syrian town of Dabiq from the Islamic State group on Sunday, dealing a major symbolic blow to the militants.
The defeat for IS came as US Secretary of State John Kerry was due to meet European allies in London as part of a new diplomatic push to end Syria's conflict, which has left more than 300,000 people dead since 2011.
The Syrian Observatory for Human Rights, Turkish state media and a rebel faction said opposition forces backed by Turkish warplanes and artillery had seized control of Dabiq on Sunday.
The town, in Syria's northern province of Aleppo, is of little strategic value.
But Dabiq holds crucial ideological importance for IS and its followers because of a Sunni prophecy that states it will be the site of an apocalyptic battle between Christian forces and Muslims.
The Observatory, a Britain-based monitoring group, said rebel forces "captured Dabiq after IS members withdrew from the area".
The Fastaqim Union, an Ankara-backed rebel faction involved in the battle, said Dabiq had fallen "after fierce clashes".
Fastaqim said rebels then went on to seize several nearby towns, including Sawran, Ihtimaylat, and Salihiyah.
Turkey's state-run Anadolu news agency also said the rebels had taken control of Dabiq and Sawran and were working to dismantle explosives laid by retreating IS fighters.
It said nine rebels were killed and 28 wounded during clashes on Saturday.
Dabiq has become a byword among IS supporters for a struggle against the West, with Washington and its allies bombing militants portrayed as modern-day Crusaders.
Earlier this week, IS downplayed the importance of the rebel advance on the town.
"These hit-and-run battles in Dabiq and its outskirts -- the lesser Dabiq battle -- will end in the greater Dabiq epic," the group said in a pamphlet published online Thursday.
Turkey launched an unprecedented operation inside Syria on August 24, helping Syrian rebels to rid its frontier of IS militants and Syrian Kurdish militia.
President Recep Tayyip Erdogan on Saturday said Turkey would push further south to create a 5,000-square-kilometre (1,900 square-mile) safe zone in Syria.
The border area has become deeply unstable, and on Sunday three Turkish police officers were killed when suspected IS suicide bombers blew themselves up during a raid on their sleeper cell in the southeastern city of Gaziantep.
According to Anadolu, Ankara-backed rebels now control 1,130-square-kilometres along the border in Aleppo province, the northern governorate that has been carved into zones of control by militants, Kurds, rebels, and regime forces.
In provincial capital Aleppo, government troops have been waging a fierce Russian-backed offensive on rebels in the eastern quarters of the city.
Fighting continued in Aleppo's northern and southern outskirts on Sunday, as well as in the city centre, according to the Observatory.
AFP's correspondent in Aleppo said there had been nearly non-stop air raids on the opposition-held half of the city since midnight.
Two people were killed Sunday in air raids on Al-Nazha, a neighbourhood in the city's east, the Observatory said.
State news agency SANA said two women were also killed and 16 people wounded in rebel fire on one government-controlled neighbourhood on Sunday.
Fighting has surged in Aleppo following the collapse last month of a ceasefire brokered by the United States and Russia, raising deep international concern.
Kerry was to fly to London on Sunday to brief Washington's European allies after "brainstorming" talks in Lausanne with the main players in Syria's conflict.
The Swiss meeting on Saturday included key rebel backers Qatar, Saudi Arabia, and Turkey, as well as regime supporters Iran and Russia.
But it did not produce a concrete plan to restore the truce that collapsed amid bitter recriminations between Washington and Moscow and new fighting on the ground.
Kerry is expected to meet on Sunday with his counterparts from Britain, France and Germany, but hopes for a breakthrough have been dim.
British foreign minister Boris Johnson is expected to propose "no-bombing zones" for Syria -- including Aleppo -- during the meeting, the Sunday Times reported.
Quoting a source close to Johnson, the report said he would seek backing from Washington and others for a proposal to threaten strikes on Syrian military sites in retaliation for bombings of certain areas or facilities such as hospitals.