So, firstly thank you for all the replies.
@Greywolf I have also seen that very good battlefield walk. As to a source I imagine it is Sears
Gettysburg p418 (again) where he has Pettigrew's aide Lewis Young recalling that Pettigrew said Brockenbrough's brigade “might follow, and if it failed to do so would not matter.” Sears then inserts some compositional information on the brigade before continuing (presumably with the previous source) “and was not to relied upon; it was virtually of no value in a fight.”
The Young quote apparently comes from
Pettigrew's Brigade at Gettysburg. No further information, date or author is given.
That said I still have some questions. What we have determined is that some people who have looked at the charge seem to think the brigade was in two halves – one commanded by Brockenbrough, one by Mayo while others think Mayo was in entire command. I wonder if indeed Mayo was not in position to attack at the right time (and it isn't Colonel Christian covering himself forty years later) did he realise he was in command of at least some of the attack. Might he have still been with his regiment? Was that why he initially couldn't be found?
If this
is the case then why was it so? Whatever the case it suggests a somewhat lacsadaisical attitude amidst the planning of the charge for surely whoever it was who was to lead the brigade should have known about it and been available at the time of the attack and they have had plenty of time to prepare. So that can't be used as an excuse.
Further while Longstreet seems to have spent some time with Pickett how much attention did he give to Pettigrew and Trimble's brigades? After all he is supposed to be in overall control. Yes Pettigrew and Trimble are new to their divisions but it all seems 'muddled' and the more I look at it there doesn't seem to be a unified PPT Charge. Instead there seem to be two distinct charges, the Pettigrew-Trimble half occurring in perhaps three distinct stages – Fry and Marshall, Mayo-Brockenbrough and then finally Trimble... which really isn't the usual narrative.
If Longstreet isn't providing coordination then surely Lee (or the mystery that is A.P. Hill) should have. We know Lee was repeatedly in the area and that Hill was at one point seen around the Louisiana monument (though there is no timing for this fleetingest of sighting).
That's my thinking any way. Yes? No?