The U.S.’s scorched earth tactics, in conjunction with the Allied mistreatment of rural residents and refugees, spurred Vietcong recruitment during the period from early 1965 to late 1967. At the beginning of 1965, Communist main force and guerrilla strength stood at 103,000. In March 1965, the month the Marines landed at Danang and U.S. air operations in South Vietnam ratcheted up, the number of Vietcong was reported to have reached 137,000. The March estimate represented a 33% increase in Communist strength in just a matter of months.
By July 1965, the U.S. revised upward its figures on enemy strength to 153,000 main forces and guerrillas. Enemy strength jumped still higher later in the year (a period that coincided with a further intensification of U.S. air and ground combat operations across South Vietnam). In the second half of 1965, U.S. intelligence estimated Vietcong in-country recruitment at 9,000 new foot soldiers per month. By the close of 1965, the Vietcong fielded an army of 230,000 regulars and part-time guerrillas. U.S. air and ground operations in 1965 failed to weaken the Vietcong. Instead, the U.S. presence did the exact opposite; it spurred a Vietcong recruitment bonanza. The Vietcong became stronger and more menacing as the U.S. build up progressed into 1966 and 1967.
At the end of 1966, the enemy force level in the South reached 288,000, an increase of nearly 60,000 from the previous year. That increase had been accomplished in spite of U.S. military’s operations that killed an estimated 100,000 enemy fighters. There was a slowdown in Vietcong recruitment in 1966, not because of a greater degree of popular support for the Saigon regime but because of the flight of upwards of 1.5 million rural refugees from Vietcong areas, which deprived the guerrillas of manpower. In 1967, Vietcong recruitment again reached a monthly peak of 9,000 per month. A Department of Defense study “…showed the number of new South Vietnamese guerrillas the Vietcong were recruiting had “gone up quite noticeably” in 1967.” Adult males from refugee families, and from homes where relatives had been killed or wounded by Allied ordnance, contributed significantly to the expansion of Vietcong ranks. Then, in September 1967, in a politically explosive report, the Central Intelligence Agency estimated total Communist strength (political and military) in the South at almost 500,000.
The dramatic rise in Vietcong strength between 1965 and late 1967 signaled Allied failure in the South Vietnamese countryside. Neither the U.S.’s military operations nor the GVN’s pacification program were taking hold in rural South Vietnam. Don Luce, whose nine years in South Vietnam gave him a deep understanding of rural life and culture, noted in the fall of 1967 that a palpable anti-Americanism and anti-GVN attitude pervaded the entire country, “I would say that there has been a very definite swing…from support and respect for Americans to one of resentment against what Americans are doing. I would say that there has been a very definite change and growing feelings against Americans in Vietnam.” Luce believed rural South Vietnam was less secure in late 1967 than it had been in 1965, especially along the coastal plain and in the Central Highlands where, “anti-Americanism has grown tenfold.”
Luce made a prediction that turned out to be remarkably prescient. Referring to the anger building across rural South Vietnam because of the destruction and dislocation wrought by American and ARVN military tactics, he said, “…if it continues…the resentment will continue to get more and more bitter…the pressures to hold this down will become stronger and stronger on the people, and…finally the whole thing will explode.” Three months later, the country did explode – with the Tet Offensive.
Back in early July 1965, before the commitment of half a million U.S. troops to the war, the State Department’s George Ball wrote President Johnson a memorandum warning him of the dangers of sending a large U.S. expeditionary force to South Vietnam, “The South Vietnamese are losing the war to the Viet Cong. No one can assure you that we can beat the Viet Cong or even force them to the conference table on our terms, no matter how many hundred thousand white, foreign (U.S.) troops we deploy…No one has demonstrated that a white ground force of whatever size can win a guerrilla war – which is at the same time a civil war between Asians – in jungle terrain in the midst of a population that refuses cooperation to the white forces (and the South Vietnamese)…Once we deploy substantial numbers of troops in combat it will become a war between the U.S. and a large part of the population of South Vietnam…Once large numbers of U.S. troops are committed to direct combat, they will begin to take heavy casualties in a war they are ill-equipped to fight in a non-cooperative if not downright hostile countryside.”
By the end of 1967, Ball’s prophecy had been borne out. A sizeable, but indeterminant, number of South Vietnam’s rural residents, as shown in the steady increases in the Vietcong’s total strength between early 1965 and late 1967, had risen up against the United States military presence. The war had become a struggle, as Ball once feared, “between the U.S. and a large part of the population of South Vietnam.” In early 1968, that hostile rural population, which included dispossessed refugees, assisted the Vietcong in attaining its greatest military success of the war.
 New York Times, “U.S. Death Toll for War is 1,350 for 1965,” January 2, 1966; The Senator Gravel Edition, The Pentagon Papers, The Defense Department History of United States Decisionmaking on Vietnam, Volume III, (Boston: Beacon Press, 1971), 406, 441; New York Times, “William Bundy Challenged on Vietcong Recruiting,” Neil Sheehan, October 17, 1967; New York Times, “Vietcong Defections Rise,” January 4, 1967; U.S. Congress, Senate, Committee on the Judiciary, Subcommittee to Investigate Problems Connected with Refugees and Escapees, “Hearings Before the Subcommittee to Investigate Problems Connected with Refugees and Escapees of the Committee on the Judiciary, United States Senate,” May 10, 18; August 16; September 21; October 9, 10, 11, 13, and 16, 1967, U.S. Senate, 90th Congress, 1st Session, (Washington, D.C.: GPO, 1968), 208.
 U.S. Congress, Senate, Committee on the Judiciary, Subcommittee to Investigate Problems Connected with Refugees and Escapees, “Hearings Before the Subcommittee to Investigate Problems Connected with Refugees and Escapees of the Committee on the Judiciary, United States Senate,” May 10, 18; August 16; September 21; October 9, 10, 11, 13, and 16, 1967, U.S. Senate, 90th Congress, 1st Session, (Washington, D.C.: GPO, 1968), 71.
 Ibid., 74.
 Ibid., 76.
 The Senator Gravel Edition, The Pentagon Papers, The Defense Department History of United States Decisionmaking on Vietnam, Volume IV, “Document 260, Memorandum for the President from George Ball, A Compromise Solution in South Vietnam, July 1, 1965,” (Boston: Beacon Press, 1971), 615-616.