During World War II, Landing Craft Utility (LCU) operated as commissioned Landing Craft Tank (LCT) under Flotilla Commanders. The LCT had an Ensign or Lieutenant Junior Grade as Commanding Officer, and operated independently or were transported aboard larger ships. At the end of the war, most of the several hundred LCU in service were decommissioned and mothballed, and a "Centralized Flotilla Command" was established at Naval Amphibious Base. This command became LCU Squadron ONE and was made up of the approximately thirty remaining LCU in the Pacific organized into three LCU divisions.

In July, 1947, a new command came into being next door to LCU Squadron ONE: Boat Unit ONE, a small craft command specializing in the Landing Craft Mechanized (LCM), and Landing Craft Vehicle/Personnel (LCVP). In 1950 in response to the outbreak of hostilities in Korea, both commands deployed craft to the Far East. Within a few months, more than 36 LCU and more than 120 LCM and LCVP were in Korea, manned by over 1.500 Sailors. These craft formed the spearhead of the amphibious assault at Inchon, and LCU Squadron ONE and Boat Unit ONE craft took part in every amphibious operation of the conflict. Following hostilitiles, a detachment of LCU Squadron ONE and Boat Unit ONE craft were permanently forward-deployed in Japan.

ACU 1 logoFollowing the conflict in Korea, LCU Squadron ONE and Boat Unit ONE craft took part in various operations around the Pacific including goodwill tours to Borneo, Singapore, Pakistan, Ceylon, Bombay and Karachi, evacuation of over 100,000 French military and Vietnamese refugees from North Vietnam, as well as providing lift for the armed withdrawal of Chinese Nationalist troops from the Tachen Islands to Taiwan. On December 5, 1958 the CNO reclassified LCU from commissioned vessels, with ENS or LTJG Commanding Officers, to combatant craft with Chief Petty Officer Craftmasters.

On October 1 1963, CNO directed a merger between Boat Unit ONE and LCU Squadron ONE in order to combine and streamline the operation of the two similar commands. Boat Unit ONE was disestablished and all boats and personnel were transferred to the three LCU Divisions. LCU Squadron ONE was renamed Assault Craft Squadron ONE (ACS-1), and the divisions changed from LCU Divisions to Assault Craft Divisions. The Squadron Commander was classified as a Commodore, with each Division having its own Commanding Officer and organizational staff. The squadron still retained its Western Pacific Detachment.

Beginning in 1963, ACS-1 craft were deployed to South Vietnam. Based at Naval Support Activity Danang, ACS-1 craft resupplied Marine forces far up river, and conducted day and night armed reconnaissance patrols. Over 20 ACS-1 Sailors were lost to hostile fire during this conflict, including the entire crew of LCU-1500. ACS-1 craft maintained a constant presence through the end of the conflict.

On 1 May 1968, CNO directed that Assault Craft Squadron ONE and its Assault Craft Divisions ELEVEN, TWELVE and THIRTEEN be disestablished, and reformed as Assault Craft Unit ONE (ACU 1). The overseas division became ACU-1 WESTPAC Detachment. The Squadron Commodore became the Commanding Officer.

On 2 August 1990, Iraqi forces invaded Kuwait and ACU-1 was one of the first Navy units to respond. Twenty LCM crews were immediately mobilized and flown to Al Jabail, Saudi Arabia, to begin offload of the Maritime Prepositioning Squadron ships. Meanwhile, on December 2, 1990 ACU-1 deployed nine LCUs and three LCMs as part of the Amphibious Task Force ONE. Within one month of arrival these craft offloaded over 20 million pounds of combat cargo.

Since September 11, 2001, ACU-1's mission set has expanded beyond the traditional assault and follow-on echelon operations to support the Global War on Terrorism. These missions include independent multi-day anti-piracy patrols, visit-board-search and seizure operations, oil platform defense, humanitarian assistance and disaster relief.


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