Detachment was attached to the 5th Marine Defense Battalion for two years. By autumn, the 18th, 19th and 25th CBs had been transferred to the Corps as combat engineers. Each was attached to a composite engineer regiment, redesignated as 3rd Battalion: 17th Marine Regiment, 18th Marine Regiment, 19th Marine Regiment, and 20th Marine Regiment. The 18th and 19th CBs each claim to have been the first CBs authorized to wear standard USMC issue. Both received their military training and USMC duffle bag at MTC New River, NC. There is no record of how many CBs received USMC issue. It is known that the 31st, 43rd, 76th, 121st and 133rd CBs received partial or complete issues. On 15 January 1944 the 142nd CB was commissioned at New River,Camp Lejeune. On 2 February that Battalion arrived at Camp Pendelton for further training, mounting out 19 April. After Guadalcanal amphibious operations became joint USMC/Seabee pairings. The 6th CB joined the 1st Marine Division after combat had started on Guadalcanal. The 18th CB was sent to join them from Fleet Marine Force depot Norfolk. Many more would follow. The 6th Special CB was tasked to the 4th Marines Depot in the Russells. November saw the 14th CB tasked to the 2nd Raider Bn on Guadalcanal. In June, the 24th CB had been tasked to the 9th Marine Defense Bn on Rendova. The 33rd and 73rd CBs had dets tasked to the 1st Pioneers as shore party on Peleliu as was the 17th Special CB colored. At Enogi Inlet on Munda, a 47th det was shore party to the 1st and 4th Marine Raiders. The 3rd Marine Div. made the Commander of the 71st CB shore party commander on Bougainville. His 71st had support from the 25th, 53rd, and 75th CBs. At Cape Torokina the 75th had 100 men volunteer to make the assault of the 3rd Marines. Also at Bougainville, the 53rd provided shore parties to the 2nd Raiders on green beach and the 3rd Raiders on Puruata Island. The 121st was formed at the CB Training Center of MTC Camp Lejuene as 3rd Bn 20th Marines. They would be shore party to the 23rd Marines on Roi-Namur, Saipan, and Tinian. When the Marine Engineer Regiments were inactivated in 1944, CBs were then tasked to Marine Divisions. For Iwo Jima, the 31st and 133rd were attached to the 4th and 5th Marine Divisions. The