Vietnam ground combat operations in 1965, and at their peak they numbered more than 500,000. The US also engaged in a sustained aerial bombing campaign. Meanwhile, China and the Soviet Union provided North Vietnam with significant material aid and 15,000 combat advisers. Communist forces supplying the Việt Cộng carried supplies along the Hồ Chí Minh trail, which passed through the Kingdom of Laos. The communists attacked South Vietnamese targets during the 1968 Tết Offensive. Although the campaign failed militarily, it shocked the American establishment, and turned US public opinion against the war. During the offensive, communist troops massacred over 3,000 civilians
1965 in the Vietnam War were destroyed. Presidential adviser and future Secretary of Defense Clark Clifford in a letter to President Johnson said, "I believe our ground forces in South Vietnam should be kept to a minimum, consistent with the protection of our installations and property in that country ... This could be a quagmire. It could turn into an open end commitment on our part that would take more and more ground troops, without a realistic hope of ultimate victory." "Quagmire" would later become a common word use to describe U.S. involvement in the Vietnam War. Eight hundred soldiers of the Australian Defence Force