The concept of riverine warfare in the Mekong Delta renewed the need for the Colleton. Having a shallow draft and flat bottom, she was well suited for the riverine environment. After extensive conversion, she was commissioned at the Philadelphia Naval Shipyard on 28 January 1967 under the command of LCDR F.R. Banbury. The first order of business after the commissioning was an extensive preparation for the transit to Vietnam.

On 6 February 1967, Colleton got underway for Norfolk, VA. to complete her fitting out by taking advantage of the logistic and training of that area. On 8 March, she got underway for Vung Tau, Republic of Vietnam. The first leg of the trip from Norfolk to the Panama Canal was utilized trying to fashion her crew into a team and getting them used to working together.

Colleton arrived at the Panama Canal during the afternoon of the 15^th and began a night transit of the Canal. After a brief stay of a few hours, at the Naval Station at Rodman, she got underway to continue on her journey.

  The second leg of her journey – Panama Canal to Pearl Harbor, Hawaii – began by "chopping" to the U.S. Pacific Fleet and was filled with drills and training. Oahu, Hawaii, finally came into sight on the morning of 4 April and Colleton entered Pearl Harbor. She got underway 8 April for the final portion of her transit to Vung Tau. Upon arrival in Vung Tau, She was "chopped" to Commander Naval Forces Vietnam and came under the operational control of Commander Riverine Flotilla One, embarked on the USS Benewah (APB-35). The Benewah and the Askari (ARL-30) had arrived earlier forming the nucleus of the growing Mobile Riverine Force (MRF). After a complete paint job (green Army olive drab), several hundred square feet of bar-armor was fabricated to cover the bridge and operations area. This had to be constructed entirely by ships company from angle iron and ½ inch steel bars. The month of May also saw the installation of 8-50 caliber and 12 7.62mm machine guns to the armament of the ship. She also acquired three ammo pontoons to be used as a mooring place for the small boats of the River Assault Squadrons and as assembling points for troops about to be embarked in the Armored Troop Carriers (Tango’s).

On 12 May, the first Army unit was embarked. The unit was the 4^th/47^th (riverine infantry) of the 2^nd Brigade 9^th Infantry Division. Five days later, River Assault Squadron 11 was also embarked. On 1 June, Colleton transported the embarked units up the Song Tien Giang to Dong Tam (30 miles southwest of Saigon). This was Colleton’s first penetration of the Delta. Four days later, the 4^th/47^th and units of River Assault Squadron 11 departed Colleton for combat operations. Colleton had no difficulty keeping up with the Army’s tempo of operations when on June 12 the Mobile Riverine Force was shifted to the Vicinity of Nha Be (5 miles southeast of Saigon) on the Song Soi Rap. A week after beginning operations in this area Colleton experienced the first anguish of war, when the 4th/47th's A-Company suffered heavy casualties. A helicopter made a total of 19 landings, each time unloading an average of 5 casualties onto the flight deck.

  On 27 July, Colleton returned to Dong Tam for a week of combat operations, then departing for Vung Tau, The main purpose in returning to Vung Tau was to concentrate the efforts of the Mobile Riverine Force in the Rung Sat Special  Zone. After a weeks stay she shifted to Song Soi Rap and Song Van Co. Ambushes from the heavily foliated banks were frequent and casualties to men and craft were common. Other operations took the ship deeper into the Delta, such as Sa Dec, Song Ham Long, and Song Co Chien, on 18 December all embarked units left the ship as she prepared for the transit to Subic Bay, arriving 24 December. see below