What was the Trinity incident? Only thing on google I could find is about the Trinity nuclear test
Trinity is the name of the book Vallee published about it. The incident itself took place in San Antonio, NM, about 28 miles from the bomb test site.
https://www.goodreads.com/book/show/58042445-trinity
Vallee’s book is about a UFO that landed adjacent to the Trinity nuclear test site in 1945—the UFO landing and retrieval by .gov is the Trinity “incident”.
https://www.amazon.com/Trinity-Best-Kept-Secret-Jacques-Vall%C3%A9e/dp/166711364X
It is the first known “crash retrieval” that is the subject of the Wilson/Davis memo and hopefully will be the subject of Congressional investigation later this year.
For a deep dive on this subject here is an excellent discussion—the pdf file is over 300 pages:
https://omega-point.medium.com/loose-threads-af8f652ee8cb