After fitting out and builder's trials, the new amphibious assault ship joined the U.S. Atlantic Fleet on 21 April 1965 and sailed for Norfolk, her homeport.
Arriving Hampton Roads the next day for training off the Virginia Capes, she departed Hampton Roads for underway training out of Guantanamo Bay, Cuba.

Guam returned to Norfolk on 5 July 1965 for intensive amphibious training.
She sailed from Hampton Roads on 29 November 1965 to participate in amphibious and anti-submarine warfare exercises en route to the Caribbean.
On 10 December 1965, Guam joined the Amphibious Ready Squadron in the Caribbean as flagship for Amphibious Squadron 12.
There she operated at peak readiness to protect the peace and security of the Caribbean and Central America.

From 16 February to 28 February 1966, Guam patrolled south of the Dominican Republic ready to land forces on the volatile island of Hispanola if necessary.
She conducted amphibious exercises until entering Philadelphia Naval Shipyard on 1 June 1966 for post shakedown availability.

She departed Philadelphia on 2 August 1966 and prepared for service as the primary recovery ship for the Gemini 11 space flight.
On 18 September, at 0959 EDT, Guam recovered Astronauts Pete Conrad and Dick Gordon 710 miles east of Cape Kennedy.
From 28 November to 12 December, Guam participated in Exercise "Lantflex 66", and on the latter date became flagship of Amphibious Squadron 8 and Caribbean Amphibious Ready Group.
After fitting out and builder's trials, the new amphibious assault ship joined the U.S. Atlantic Fleet on 21 April 1965 and sailed for Norfolk, her homeport. Arriving Hampton Roads the next day for training off the Virginia Capes, she departed Hampton Roads for underway training out of Guantanamo Bay, Cuba.
Guam returned to Norfolk on 5 July 1965 for intensive amphibious training. She sailed from Hampton Roads on 29 November 1965 to participate in amphibious and anti-submarine warfare exercises en route to the Caribbean. On 10 December 1965, Guam joined the Amphibious Ready Squadron in the Caribbean as flagship for Amphibious Squadron 12. There she operated at peak readiness to protect the peace and security of the Caribbean and Central America.
From 16 February to 28 February 1966, Guam patrolled south of the Dominican Republic ready to land forces on the volatile island of Hispanola if necessary. She conducted amphibious exercises until entering Philadelphia Naval Shipyard on 1 June 1966 for post shakedown availability.
She departed Philadelphia on 2 August 1966 and prepared for service as the primary recovery ship for the Gemini 11 space flight. On 18 September, at 0959 EDT, Guam recovered Astronauts Pete Conrad and Dick Gordon 710 miles east of Cape Kennedy. From 28 November to 12 December, Guam participated in Exercise "Lantflex 66", and on the latter date became flagship of Amphibious Squadron 8 and Caribbean Amphibious Ready Group.
USS Guam (LPH-9)