1961 and 1964 the Army's strength rose from about 850,000 to nearly a million men." The numbers for U.S. troops deployed to Vietnam during the same period were much lower: 2,000 in 1961, rising rapidly to 16,500 in 1964. During this phase, the use of captured equipment decreased, while greater numbers of ammunition and supplies were required to maintain regular units. Group 559 was tasked with expanding the Ho Chi Minh trail, in light of the near constant bombardment by US warplanes. The war had begun to shift into the final, conventional warfare phase of Hanoi's three-stage protracted warfare model. The Viet Cong was now tasked with destroying the ARVN and capturing and holding areas; however, the Viet Cong was not yet strong enough to assault major towns and cities. In December 1964, ARVN forces had suffered heavy losses at the Battle of Bình Giã, in a battle that both sides viewed as a watershed. Previously, the VC had utilised hit-and-run guerrilla tactics. At Binh Gia, however, they had defeated a strong ARVN force in a conventional battle and remained in the field for four days. Tellingly, South Vietnamese forces were again defeated in June 1965 at the Battle of Đồng Xoài. American ground war On 8 March 1965, 3,500 U.S. Marines were landed near Da Nang, South Vietnam. This marked the beginning of the American ground war. U.S. public opinion overwhelmingly supported the deployment. The Marines' initial assignment was the defense of Da Nang Air Base. The first deployment of 3,500 in March 1965 was increased to nearly 200,000 by December. The U.S. military had long been schooled in offensive warfare. Regardless of political policies, U.S. commanders were institutionally and psychologically unsuited to a defensive mission. General William Westmoreland informed Admiral U. S. Grant Sharp Jr., commander of U.S. Pacific forces, that the situation was critical. He said, "I am convinced that U.S. troops with their energy, mobility, and firepower can successfully take the fight to the NLF (Viet Cong)". With this recommendation, Westmoreland was advocating an aggressive departure from America's defensive posture and the sidelining of the South Vietnamese. By ignoring ARVN units, the U.S. commitment became open-ended. Westmoreland outlined a three-point plan to win the war: Phase 1. Commitment of U.S. (and other free world) forces necessary to halt the losing trend by the end of 1965. Phase 2. U.S. and allied forces mount major offensive actions