The date question is perhaps best covered by Timothy Good in his Alien Base book (1998), to quote: "Another of my questions dealt with the fact that, in all editions of his first book, The White Sands Incident (first published in 1954), the date of the incident is given as 4 July 1950. Yet 10 years after publication he admitted that the incident actually occurred on July 4th, 1949.

" 'I had to change it,' he explained. 'In the last edition [1966], I told the publisher to change it, but he decided this might not be a good for publicity, and he kept it to 1950 after I'd said to change it, because there was now no need to hide the fact that it was 1949.'

" 'So there was a reason?' I asked.

" 'There was a reason,' Dan replied, 'because it turned out to be a year later then he had originally planned - that Alan could be here.  He thought it could be done in four years; it actually took five years.  Now, had the Pentagon, for example, taken this book seriously, at the time there was a pretty good chance they could have tracked him down.  There had to be an escape mechanism.  The fact is that on the evening of the Fourth of July 1950, I was not at White Sands - I didn't arrive there until later in July.  And everyone at White Sands Proving Grounds and in Aerojet knows that.'"

It was first in the 1960s that Daniel mentioned the date was in the 1950s on the Ben Hunter show in July of 1960: