May 19, 1967. Secretary of Defense Robert McNamara drafts a 22-page memo to LBJ in response to the request from General Westmoreland and Admiral Sharp for an additional 200,000 men. McNamara later described the memo as having “crystallized my growing doubts and set the stage for the increasingly sharp debate that followed.”

McNamara came down decisively against the large increase, in part due to a worsening domestic climate:

“The Vietnam war is unpopular in this country. It is becoming increasingly unpopular as it escalates—causing more American casualties, more fear of its growing into a wider war, more privation of the domestic sector, and more distress at the amount of suffering being visited on the non-combatants in Vietnam, South and North. Most Americans do not know how we got where we are, and most, without knowing why, but taking advantage of hindsight, are convinced that somehow we should not have gotten this deeply in. All want the war ended and expect their President to end it. Successfully. Or else.

This state of mind in the US generates impatience in the political structure of the United States. It unfortunately also generates patience in Hanoi.”

You can read the whole memo here. LBJ Presidential Library photo of McNamara in 1964 #w482-32a. McNamara quote Robert S. McNamara with Brian VanDeMark, In Retrospect: The Tragedy and Lessons of Vietnam, New York: Random House, 1995, p. 266.