Houthi militants, military sources said on Monday.
Scores from the militants and dissident forces backing them were killed and injured in the battles and many others fled, the sources said.
The forces are combing the areas where the base and brigades are located and are now seeking to drive all militants from Lahj, they elaborated.
Lahj will be the second southern city to be retaken from the Houthis after Aden which was cleaned up a few weeks ago.
President Abd Rabbuh Mansour Hadi said the victory will not stop at the Al-Anad base but rather the forces will continue the fight until they liberate the whole country from the Houthi militants.
Al-Anad is the country's largest base and retaking it will help protect Lahj and nearby cities especially Aden and Taiz, observers said today.
On Monday, the battles between the forces and the Houthis continued in other cities coinciding with Arab airstrikes targeting the Houthis.