My point was that Mosby cannot be considered a primary source--one with on-site knowledge of what occurred at or around Gettysburg. At best, his memoir, at least the part that concerns Stuart, is a secondary source and his opinion of what Stuart did or didn't do at Gettysburg.

"It is for each of us to judge the validity of the evidence presented, not on the basis of who writes it, or when, but on the basis of does it fit the known facts."

You are right. In ananlyzing any source matererial, one must determine whether what we have read/are reading is fact, opinion, or propaganda. And because so much propaganda was written after the war, one must be careful not to confuse propaganda and opinion with the facts as to what actually occurred during the war years.

A good article on how to use one's critical thinking skills when examining research resources is here:

http://www.library.cornell.edu/olinuris/ref/research/skill26.htm#LinkCoverage

Enuf said.