He hoped that he could get a deal with the North Vietnamese. He thought that with a gradual application of power that the enemy would tire soon enough when combined with a promise of aid for development after they signed a peace treaty. He never understood the North Vietnamese, and after the Tet Offensive he thought he was up the creek without a paddle.
It's only within the last few years or so that I learned what LBJ was thinking at that time by listening to some of the audiotapes and some historians on C-SPAN. Robert Dallek is a historian who is working on a multiple volume biography of LBJ. I think the volume he's working on now is how Johnson dealt with Vietnam. It will be interesting to see what he says.
Here's the link for the following:
Johnson, like Kennedy before him and Nixon after, tape-recorded many of his meetings. On May 27, 1964, he said to Bundy (as transcribed by Michael Beschloss in his book Taking Charge: The Johnson White House Tapes 1963-64):
It looks to me like we're getting into another Korea. It just worries the hell out of me. I don't see what we can ever hope to get out of there with, once we're committed. I believe that the Chinese Communists are coming into it. I don't think that we can fight them 10,000 miles away from home. I don't think it's worth fighting for and I don't think that we can get out. It's just the biggest damned mess that I ever saw.
If you go to Washington D.C. and visit the "WALL", please remember the Great Society and all the other liberal follies those folks paid for. I believe LBJ completed the transformation of the rats into a socialist party that was started under FDR. I think Clinton is evil, but not as bad as LBJ.