Final answer:
General William Westmoreland delivered speeches to reassure the American public and maintain support for the Vietnam War effort, promoting the government's view that the war was winnable despite growing public skepticism.
Step-by-step explanation:
President Johnson had General William Westmoreland give speeches about U.S. progress in Vietnam in order to reassure the American public about the war effort. This approach was used during a time when the American public's support for the Vietnam War began to wane due to the increasing number of U.S. casualties and the perception of a lack of clear progress.
Westmoreland's speeches aligned with the government's official stance that the war was winnable and that the United States was making significant headway in the conflict, a view that was increasingly scrutinized in light of the contradicting footage and reports coming from Vietnam.