Most of the training was done on the Potomac, the Chesapeake Bay area (upper Chesapeake River and Norfolk), and NAB Little Creek, Virginia; and off the coast of Maryland, particularly St. Mary's and Solomon Island, which became their simulated battleground as squads attempted to scout each other's defenses. Submarine training took place at Naval Submarine Base New London, Connecticut in June 1942.
The Observer Group began to conduct reconnaissance exercises on both the Atlantic and the Caribbean, (just as the Fleet Marine Force's Fleet Landing Exercises had done a few years before) by the Marines' Platoon Sergeant Russell Corey. He trained the Observer Group in hands-on work as sea abroad fleet submarines and in the tower for instructions in the Momsen lung. Another Marine by the name of Sergeant Thomas L. Curtis was selected from the Observer Group and was sent to England to train with the Royal Marines and subsequently was transferred to Office of Strategic Services (precursor to the Central Intelligence Agency).
They began experimenting in the methodology for launching reconnaissance from the sea and testing various equipments. Inflatable rubber boats were mostly used, although kayaks and canvas folding boats had been tested but were rejected. The determining criteria for boat selection was that recon boats needed to fit through the small hatches of fleet submarines while carrying weapons and equipment and be capable of handling related loads. The men of the 4th Marines were trained and taught knife fighting and escaping techniques in Shanghai by British Commando Instructor Lieutenant Colonel William E. Fairbairn, formerly an Inspector of the Shanghai Municipal Police. Fairbairn was one of the developers, along with another Inspector, Eric A. Sykes that introduced the fighting knife designed by Major Sam Yeats of 4th Marines, which later became the Fairbairn-Sykes Fighting Knife that were used by the Marine Recon units and later adopted by the Marine Raiders and the Paramarines during World War II.[1] Around this time the Observer Group was sent to the School for the Federal Bureau of Investigation, which also shared the same base at Quantico, and were trained by FBI Agents for two weeks in the rudiments of jujutsu, pistol shooting from the hip, and operation of the Thompson submachine gun, or TSMG.
While the Observer Group was practicing their operational skills, the Intelligence Officers had worked out the tactical utilization of amphibious reconnaissance developing a new doctrine and organizational plan for the Fleet Marine Force. With the assignment to the United States Army of primary responsibility for the Atlantic (the Amphibious Corps, Atlantic Fleet) and to the United States Navy of primary responsibility for the Pacific (the Amphibious Corps, Pacific Fleet), the joint command under General Smith divided as he relocated from Quantico to Camp Elliott, northeast of San Diego, California.
In August 1942, both the Army and Navy separated their joint effort and continued its planning for North Africa in Operation Torch. By September, the Navy established the Amphibious Scout and Raider School on NAB Little Creek, VA, subsequently forming the Navy Scouts & Raiders unit. On 7 January 1943, the remaining Observer Group, with Captain Jones commanding, formed the Amphibious Reconnaissance Company, Expeditionary Troops, Amphibious Corps Pacific Fleet (ACPF) under the command of Capt. James L. Jones, Sr.
