January 31, 1968: During the Vietnamese new year's celebration, Tet, North Vietnamese forces carry out more than 150 simultaneous attacks throughout South Vietnam, taking the U.S. almost completely by surprise. On the second day of the Tet offensive, AP photographer Eddie Adams photographs South Vietnamese Colonel Nguyen Ngog Loan executing a Viet Cong prisoner on the streets of Saigon. The photograph is instrumental in turning U.S. public opinion against the war, wins the 1969 Pulitzer Prize for Spot News Photography, and haunts Loan and Adams (who later became friends) for the rest of their lives.