After shakedown in the Atlantic, Hollis made two escort voyages along the East Coast and then reported to Quonset Point, R.I., to assist in sonic research.

The aim was to find countermeasures for the German acoustic torpedo, and the destroyer escort remained on this important duty until 28 May, when she sailed to Casablanca in an aircraft carrier screen.

In the months that followed, as the offensive gained momentum, Hollis continued her role as an escort in the Mediterranean, ensuring the flow of vital supplies and men.

Converted to a UDT flagship, Hollis sailed to Eniwetok and Guam as the Japanese were accepting surrender terms, arriving Apra Harbor on 23 August 1945.

With the increase in fleet strength brought about by the Korean War, Hollis recommissioned on 6 April 1951 and conducted shakedown training out of Norfolk, Virginia.

After attending a special course in communications, Ensign Hollis reported to battleship USS Arizona in September and was promoted to Lieutenant (Junior Grade) on 15 November.