April 17th marks the 50th anniversary of what many consider the first major protest against the Vietnam War.
The March Against the Vietnam War was held in Washington D.C. in 1965.
Members of some of the groups who organized it say up to 25,000 attended.
The men say the protest helped bring the anti-war movement to national attention and sway public opinion against the war.
They say today's protestors can have a similar effect.
"If people are organized and they're organized strong enough and in greater numbers, great numbers it can make a difference," said Ted Reich.
"We see every day that demonstrations change the face of things, that people who are getting the short end of the stick can make a very big difference, that we have allies everywhere," said Daniel Millstone.
This month also marks the 40th anniversary of the fall of Saigon in 1975.