Who served as President of the United States during a period marked by both significant economic prosperity and the escalation of the Vietnam War, facing considerable social unrest and anti-war protests?

1. He took office following the assassination of his predecessor.
2. His domestic policy initiatives were often referred to as the 'Great Society'.
3. He signed the Civil Rights Act of 1964.
4. He decided not to seek re-election in 1968 due to the political climate.