Amphibious Warfare: First World War

1914 - Culebra Maneuver: USMC forms Advanced Base Force

By 1913, the Navy and Marine Corps had agreed on the approximate size and organization of the Advanced Base Force. Two fixed-defense regiments, each approximately 1,250 men strong, would guard advanced bases from attack by enemy warships and landing forces using large-caliber naval guns temporarily emplaced ashore, and sea mines. Artillery, engineer, signal, searchlight, and mining companies would comprise each regiment. One unit would be based on the east coast at Philadelphia, while the west coast regiment would be split between the island of Guam in the Mariana Islands and Mare Island Shipyard in California. In addition, the General Board, a high-level naval advisory board to the Secretary of the Navy, called for the establishment of two additional 1,250-man mobile defense regiments to augment the fixed defense units.

These requirements represented more of a final goal than an objective that would be easily reached. Congress had been slow to appropriate funds for Advanced Base Force equipment, and Navy bureaus had not placed Marine Corps needs high on their list of priorities. For its part, the Marine Corps had a difficult time mustering the manpower for the standing base-defense units. Never possessing more than 10,000 men during the first decade and a half of the 20th century, the service also had to maintain expeditionary forces overseas in the Philippines and the Caribbean and provide detachments for service on board warships and in shipyards. Even with these obstacles, however, the nucleus of the Advanced Base Force was taking shape.

Consequently, the General Board decided that the force should be integrated into fleet maneuvers, in particular the Atlantic Fleet exercises scheduled for the winter of 1913-1914. The Navy and Marines spent much of 1913 gathering together the men, materiel, and ships needed to make this a reality. The return of a provisional Marine brigade from Guantanamo Bay, Cuba provided additional manpower. The Navy's Bureau of Ordnance transferred weapons to the force that, while mostly obsolete, at least allowed the Marines to set up realistic shore defenses. The Navy also detailed a former small ocean liner-turned-transport, Hancock, to embark the fixed defense regiment in Philadelphia, and another small transport, Prairie, to carry a mobile-defense regiment.

Designed to exercise an actual navy war plan for a conflict in the Caribbean with Germany, the fleet maneuver scenario involved the establishment of an anchorage at the island of Culebra off Puerto Rico. The Marine base-defense units would deploy ashore to fortify the island and protect the fleet auxiliary support ships in the anchorage. A simulated enemy force would make several attempts to assault and capture the island; the Marines' task was to thwart these efforts. The expeditionary aspect of the exercise began on 3 January 1914. The fixed-defense regiment had begun a fairly sophisticated combat loading of its equipment on Hancock in mid-December.

This load-out included two fragile biplanes and their Navy crews, which would be used to spot for Marine gunners. The commander of the entire Marine brigade, Colonel George Barnett (named to be the next Marine Corps Commandant during the exercise) and his staff also embarked on board Hancock. Meanwhile, a mobile-defense regiment - four infantry and one automatic rifle company under Lieutenant Colonel John A. Lejeune, forward deployed to Pensacola, Florida for potential use in Mexico - boarded Prairie.

Photo of Major General George Barnett

Major General George Barnett, 12th Commandant of the Marine Corps,
commanded the Marine defenders of Culebra island during the 1913-1914 exercises.
U.S. Marine Corps.

The Marines arrived at Culebra on 10 January, and by the 18th had moved their equipment ashore and set up defensive positions. That night, Atlantic Fleet units initiated their simulated attacks on the island. The first phase involved Navy warships "bombarding" the island, vigorously opposed by Marine gunners. The second phase included a landing carried out by 1,200 sailors and Marines drawn from various ships companies. Again, Culebra's defenders responded effectively, leading Navy umpires to conclude that, had the conflict been real, the landing force would have been repulsed.

The exercise continued for another week, and the Marine regiments continued their training on Culebra for another two weeks after that. Both units then sailed for the U.S. Gulf Coast where they remained on-call for possible deployment to Mexico. By April, both units were on the move to Mexican waters, with the fixed-defense regiment reorganized as an infantry unit.

The 1914 Culebra exercise proved the value to the U.S. fleet of maintaining units trained for advanced base defense. The General Board recommended that this capability continue to be honed during fleet maneuvers every year, and Marine Corps units were kept organized for this mission until the 1920s.

In hindsight, however, the base-defense aspect of the maneuvers proved to be less important to the future of U.S. amphibious assault than that of Marines moving as combat-ready units, with their equipment, on board Navy transports - not as small detachments onboard capital warships. This arrangement, when combined with the expeditionary capabilities that Marine units had already displayed in the Caribbean and Asia, eventually would develop into a vital U.S. power projection capability.


Lieutenant Colonel Kenneth J. Clifford, Progress and Purpose: A Developmental History of the United States Marine Corps, 1900-1970 (Washington, DC: History and Museums Division, Headquarters, U.S. Marine Corps,

Graham A. Cosmas and Jack Shulimson, "The Culebra Maneuver and the Formation of the U.S. Marine Corps's Advanced Base Force," in Lieutenant Colonel Merrill L. Bartlett, USMC (ret.), ed., Assault from the Sea (Annapolis, MD: Naval Institute Press, 1983).

Allan R. Millett, Semper Fidelis: A History of the United States Marine Corps (New York: The Free Press, 1991).

Back to Top