The watery, heavily vegetated marshlands of the Mekong Delta served as a formidable natural defense for Viet Cong units in the region, and the waterways served as the transportation corridor for Communist forces.. The Mobile Riverine Force formed the bulk of what came to be known as the Brown Water Navy, and was key to American efforts in the region. Elsewhere in Vietnam, dense jungle growth also presented barriers for rapid movement of allied troops, resulting in helicopters taking increasingly important roles with the military, serving as troop transports, cargo carriers, medical evacuation units, and even aerial gunships. AUTHOR: An avid military vehicle enthusiast whose collection includes 10 Vietnam-era vehicles, it is not surprising that most of his 100+ published books focus on US military weapons of war. In June 2015, he was presented the coveted Bart Vanderveen Award by the Military Vehicle Preservation Association, given in recognition of "…the individual who has contributed the most to the historic preservation of military vehicles worldwide." Some of David Doyle's published works are - U.S Vehicles and Heavy Weapons of the Vietnam War; M65 Atomic Canon; M7 Priest, M12 Gun Motor Carriage; U.S. Half-Track Vehicles In Action; The Complete DUKW Historical Reference; P-47 Thunderbolt In Action; USS Iowa (BB-61). 250 colour and b/w illustrations