Chicago:1968 © Len Kody and Jenny Frison
Johnson's withdrawal from the race threatened the underpinnings of the entire protest movement. LBJ had become the symbol of everything the Mobilization and the Yippies were against. And until he suddenly announced that he would not be running, everybody just assumed that Lyndon Johnson - the sitting President - and Hubert Humphrey - his Vice President - would be nominated by the Democrats in Chicago for a chance at a second full term. So the protests were being planned as a symbolic rejection of LBJ and his pro-war policies.
Without the Johnson bogeyman to galvanize the vitriol of the left, much of the thrust had been taken out of Yippie for a time. What was building steam as the battle of the century - Johnson vs. the Counter Culture - had become anticlimax by the end of March.
So, LBJ had, indeed, out-Yippied the Yippies. If the rest of 1968 had been uneventful, the Yippes may have remained flaccid, and the passions unleashed that summer may have lay unexpressed for another generation or two.