The Dawn of Islam Brigade, a rebel faction from southern Syria formed in December and now affiliated with the Free Syrian Army, led the battle for Dael, according to Internet videos from the town, including one showing a Syrian Army tank in flames.

Rami Abdulrahman, the founder of the Syrian Observatory, said in a telephone interview that the seizure of Dael was significant because it could prevent the military from using the north-south highway for funneling war matériel between Damascus and Dara’a. The highway is also an important doorway to Jordan, which Mr. Abdulrahman said was a point of entry for weapons and ammunition that is channeled to the rebels.

“The importance of Dael is its location,” he said.

Outside experts who have been following the progression of the war also said the seizure of Dael was significant because fighting in that area of southern Syria has been raging for weeks. Andrew J. Tabler, a senior fellow at the Washington Institute for Near East Policy, said in an e-mail, “It’s a big win in a long war, and a loss of that area is strategic.”

There was no independent way to confirm whether the rebel occupation of Dael was temporary, or to ascertain whether the military would respond with overwhelming force, as Mr. Assad’s forces have done many times before in efforts to retake contested areas.

Mohammed Qadah, a Dara’a representative of the National Coalition for Syrian Revolutionary and Opposition Forces, the main opposition group, said in a telephone interview that the military had been “raining mortars and shells” on Dael since rebels had destroyed the last of the military checkpoints early Friday, and that at least two other villages on the Damascus-Dara’a highway remained under government control.