Final answer:
The Pentagon Papers leak by Daniel Ellsberg in 1971 exposed the U.S. government's deception about the Vietnam War progress to the American public.
Explanation:
The event during the Vietnam War that revealed to the American public that the U.S. government had been lying to them about the progress of the war was the Pentagon Papers leak by Daniel Ellsberg in 1971. These top-secret documents demonstrated a history of government misinformation and the exaggeration of American victories in Vietnam to the public.
Learn more about Pentagon Papers and Vietnam War here:
https://brainly.com/question/31796218
