He received further instruction with the Advanced Carrier Training Group and reported to USS Enterprise on 3 April 1942, joining Bombing Squadron 6 (VB-6) flying the Douglas SBD Dauntless dive bomber.

Flying from Enterprise during the Battle of Midway on 5 June 1942, he flew with the third division of VB-6 in their attack against the Imperial Japanese Navy aircraft carrier Akagi.

Varian was laid down on 27 August 1943 at Orange, Texas, by the Consolidated Steel Corp.; launched on 6 November 1943; sponsored by Mrs. Arnold F. Brunkow, sister of the late Ens.

She then conducted two more round-trip convoy missions, with UGS/GUS-51 from mid-August to mid-September and with UGS/GUS-58 until mid-November, before she was assigned to the first "hunter-killer" group – formed on 30 November 1944 to track down and destroy enemy submarines.

They received special instruction, principally in high-frequency direction finding and gunnery; and spent 60 hours perfecting unit tactics for coordinated attacks on maneuvering submarines.

Shifting to Miami, Florida, soon thereafter, the destroyer escort operated in a training role, providing practical experience for newly commissioned officers until 16 July.

On 2 September, the ship departed Culebra, Puerto Rico, and she steamed north to New London, Conn., for training duty with Atlantic Fleet submarines.

At New Haven, Connecticut, for Navy Day festivities, Varian subsequently sailed south for inactivation at Green Cove Springs near Jacksonville, Florida.