General opposition to the war was for several reasons:
Events in Vietnam like the Tet Offensive, Bombing of Cambodia
The high death toll affecting family members
Increased taxes to pay for the war
Civil Rights Movement:
Leaders of the movement like MartinLutherKing, MohammedAli and the BlackPanthers all voiced opposition to fighting for America abroad when they faced racism at home
Media coverage:
The Vietnam War was the first televised war, which allowed Americans to watch the war from home
They also saw reports on anti-war protests
Lies:
People realised that the government was not telling the whole truth about the war and began to losefaith
The Draft:
Men over 18 could be drafted into military service at any time and sent to Vietnam to fight with basic training
People felt this was unfair as they were too young and would be more likely to die without proper training
Drafting also targeted poor, black men
the student movement:
students opposed the war through methods used by civil rights campaigners
student protests got alot of attention, because most protestors were white and middle class