On March 16, 1968, during a roughly four-hour operation in the Vietnamese village of Son My, American soldiers killed approximately 504 civilians, including pregnant women and infants, gang-raped women and burned a village to ashes. Calley, though a low-ranking officer in Charlie Company, stood out because of the sheer number of civilians he was accused of killing and ordering killed.Wikipedia:
The red-haired Miami native known to friends as Rusty became the face of the massacre, which was named after one of the sub-hamlets where the killings took place, My Lai 4. His story dominated headlines, along with the Apollo 12 moon landing and the trial of Charles Manson. His case became a kind of litmus test for American values, a question not only of who was to blame for My Lai, but how America should conduct war and what constitutes a war crime.
Politicians, noting the anger of their constituents, made gestures of their own. Indiana Gov. Edgar Whitcomb ordered the state’s flags to fly at half-staff. Gov. John Bell Williams of Mississippi said his state was “about ready to secede from the Union” over the Calley verdict. Gov. Jimmy Carter, the future president, urged his fellow Georgians to “honor the flag as Rusty had done.” Local leaders across the country demanded that President Nixon pardon Calley.
Georgia's Governor, Jimmy Carter, future President of the United States, instituted American Fighting Man's Day, and asked Georgians to drive for a week with their lights on. Indiana's Governor Edgar Whitcomb asked that all state flags be flown at half-staff for Calley, and the governors of Utah and Mississippi also publicly disagreed with the verdict. The legislatures of Arkansas, Kansas, Texas, New Jersey, and South Carolina requested clemency for Calley. Alabama's governor, George Wallace, visited Calley in the stockade and requested that President Richard Nixon pardon him.