During the Goldwater-LBJ race, the Democrats told everyone in their TV ads that if they voted for Goldwater, there would be 'half a million men in Viet Nam within 6 months".  I saw those ads.  

Sure enough, LBJ had 500,000 men in Viet Nam within 6 months and even though during the election on October  21, 1964 in Akron, Ohio, he said:

"we are not about to send American boys 9 or 10,000 miles away from home to do what Asian boys ought to be doing for themselves." 

Presidents lie---sometimes even to themselves.