Certainely those others would have helped..and probably would have added enough to take the position.
Armistead:
The number of actually captured is difficult to ascertain..because missing and unaccounted for meant any not answering the roll the next time it was taken.
Some no doubt were dead..some in Federal hospitals,some wounded/helpless and unfound,some stragglers and some deserted.
Odds are though that the majority listed as missing were in fact captured.
Armistead's Brigade is a special case.:
According to Krick's The Gettysburg Death roster/The Confederate Dead at Gettysburg...Armistead's Brigade listed 88-Killed,491-Wounded,and 643 missing.
These numbers however are amongst the most unreliable of all
CS/Gettysburg returns,
with virtually every senior officer gone...reports were not filed.
The real numbers will probably never be known..short of a Herculian effort by a gifted historian/researcher and if other records can be found.
VS..etc
