What happened in 1968? Operation Rolling Thunder began. Martin Luther King, Jr. was assassinated. Robert F. Kennedy was assassinated. Violence erupted outside the Democratic National Convention in Chicago.

The answer to your question is,

Martin Luther King Jr. was assassinated.

-Mabel <3

In 1968 both Robert F. Kennedy and Martin Luther King Jr. we're assassinated and Violence erupted outside the Democratic National Convention in Chicago, the only event not happening in 1968 is the beginning of Operation Rolling Thunder because it began in 1965 I believe and ultimately ended in 1968.