With your historian's hat on, briefly write the single most significant lesson learned regarding presidential leadership in the Vietnam War.
The original question had to be edited. I invite you to resubmit the other parts as individual questions. One of the most significant lessons learned from Vietnam with regards to Presidential leadership is that the President must maintain a transparent connection with the people during times of war. Both Presidents Johnson and Nixon learned this through the Vietnam Experience.
President Johnson was able to convince the American public of the need to be in Vietnam at the war's exposition. For the most part, the Johnson Administration's entering into war enjoyed American support. The challenge in Presidential Leadership that Johnson faced existed in not having a clear exit policy or a lucid metric for victory. As the war progressed, Johnson's Presidential leadership capacity diminished because he was unable to articulate these realities to the public. The inability for the President to communicate what constituted victory, how the war was progressing, or even if mistakes were made damaged his credibility with the public. Even his successor, Richard Nixon, noted this wounded element of Presidential leadership:
"I'm not going to end up like [President] Lyndon Johnson, holed up in the White House, afraid to show my face on the street," said Nixon. "I'm going to end the war in Vietnam. Fast."
For his part, President Nixon also understood the need to clearly communicate expectations with the American people regarding his administration's involvement in Vietnam. Recognizing clearly that the anti- war sentiment in America was proving to be a challenge, Nixon's "Silent Majority" speech was intended to use clear communication about the war's objectives as away to bolster his Presidential leadership capacity. President Johnson was never able to do this. He was never able to shift the dialogue in a way where clarity in his leadership was evident. Almost seeming to become overwhelmed with the complexity of Vietnam, President Johnson acquiesced to it. President Nixon was able to construct the facade of clear communication in pivoting his expectations towards this "silent majority" and the prestige of America. While it was a politically calculated tool, President Nixon was able to use clear communication as a way to enhance his presidential leadership.
The challenges in Vietnam for both Presidents underscored the importance of clarity in communication for Presidential leadership to be effective. There can be a direct line drawn between clarity of expectations with the American people and their support. When President Johnson was unable to do this, he lost credibility with the American people and his leadership capacity was forever impacted. When President Nixon was able to develop a way in which this clarity was framed effectively, his Presidential leadership capacity increased.