tested, but none reached production stage due to lack of funding. Realizing that acquisition of new vehicles was unlikely, the Marines modernized some of the LVT-3s and LVT(A)-5s under projects SCB-60B and SCB-60A respectively, and kept them in service until the late 1950s. Combat history Guadalcanal USMC LVT-1s were mainly used for logistical support at Guadalcanal. LVT-1 proved in this campaign its tactical capabilities, versatility and potential for amphibious operations. As LVT-1s were unarmed, the Marines decided to arm them using any available machine gun. Each one was armed with three .30-caliber machine guns (sometimes water-cooled models) and a .50-caliber machine gun. Organization of LVTs of the Amphibian Tractor Battalions for the assault: Company "A" of 1st Battalion with thirty LVT-1 was assigned to the 5th Marines which was to land on Guadalcanal. A platoon of LVT-1s assigned to 2nd Marine Battalion went ashore on Tulagi. Company "B" was assigned to the 1st Marine Regiment. The remainder of the 1st Battalion remained with the 1st Division's support group. Company "A" of the 2nd Battalion was assigned to 2nd Marine Regiment, the landing force reserve. Tarawa In the amphibious assault on Tarawa in late 1943, the LVTs were first used for amphibious assault in order to negotiate the barrier reef, where several Higgins Boats had run aground and became stuck, and arrive to the most heavily defended beaches the Americans ever met in the Pacific. This was also the first use of the LVT-2 Water Buffalo in combat. 2nd Amphibian Tractor Battalion LVTs took part in the first, second, and third waves of landings and carried the continuous supply of ammunition, reinforcements, and ferrying back of the wounded. Of 125 vehicles used (50 new LVT-2s and 75 LVT-1s), only 35 remained operational by the end of the first day, continuing to ferry men and supplies across the coral reef and through the shallows to the beach. The 2nd Amphibian Tractor Battalion had only about 79 LVT-1s and 50 LVT-2s (directly shipped from San Diego) available for the assault. Most of the troops had to disembark from LCVP "Higgins boats" and wade across the reef chest-deep or higher water while under heavy enemy fire. American casualties were very heavy and many who made to the beach alive had lost their rifles and other essential gear. Developments in the Pacific After Tarawa, many changes were made. The USMC recommended that a battalion of