POLITICS AND RHETORIC: Reading an essay by Edward Mendelson on W.H. Auden's habits of revision, I was reminded of this:
The 'Daisy' ad is infamous, and for good reason. Mendelson pointed out, though, that LBJ is borrowing the most famous line from Auden's most famous poem: "We must love one another or die." This line caused Auden no end of trouble. It was pointed out to him that the choice was false: we all must die anyway, whether we have loved one another or not. He changed the line to 'We must love one another and die." That doesn't work, either. The line has rhetorical power, so much that one will only notice later, if at all, that it is false.
No change could save the line, or the stanza to which it functions as the close, or indeed the whole poem. "September 1, 1939" doesn't appear in any of Auden's later compilations (interestingly, it only is dropped beginning in 1965, though I can't find any indication as to whether the LBJ ad played a role).