1968 was a very bad year:
The Tet offensive in January 1968 had left many Americans shocked and doubting that victory in Vietnam was possible. In April, the Rev. Martin Luther King was assassinated, and streets throughout the nation erupted in fire and fury. Sen. Robert F. Kennedy was gunned down two months later.
That summer, the nation watched in horror as police and anti-war protesters battled in the streets of Chicago during the Democratic National Convention.
Besides the quoted events, additional bad news was tons of events related to Viet Nam such the U.S. sends an additional 10,500 soliders over there, the massacre of +400 unarmed South Vietnamese civilians in the village of My Lai and the infamous photo of Saigon police chief Nguyen Ngoc Loan executing a Viet Cong officer with a pistol shot to the head is publicized, France detonates a hydrogen bomb and becomes a nuclear power thereby extending nuclear proliferation, the USSR invades Czechoslovakia, hijackers murdered 21 Pan Am passengers in Pakistan and Vince Lombardi resigns as coach of the Green Bay Packers. Sorry, the last one is true, but not catastrophic. It really was a very bad year with one notable exception.
Astronaut Frank Borman's favorite telegram after the mission said
"Thank you, Apollo 8. You saved 1968."
It was the Apollo 8 mission which took one of the most famous photos of the entire Apollo program:
Earth rise.