What 1968 military campaign, launched by North Vietnamese forces during a major holiday, is credited with turning U.S. public opinion against the Vietnam War?

Tet Offensive

Named for Tet, the Vietnamese Lunar New Year, the offensive began during a period when holiday truces had been announced. Communist forces suffered a severe tactical defeat, but the attacks undermined official claims of steady U.S. progress and accelerated the public turn against the war.