1968 Additional troops ordered to South Vietnam

As an emergency measure in response to the 1968 communist Tet Offensive, Secretary of Defense Robert McNamara approves the deployment of 10,500 troops to cope with threats of a second offensive. The Joint Chiefs of Staff, who had argued against dispatching any reinforcements at the time because it would seriously deplete the strategic reserve, immediately sent McNamara a memorandum asking that 46,300 reservists and former servicemen be activated. Not wanting to test public opinion on what would no doubt be a controversial move, Johnson consigned the issue of the reservists to “study.” Ultimately, he decided against a large-scale activation of the reserve forces.

Source: www.history.com