The first of Henry Heth's people engaged on the first day was a brigade of Tenneseans and Alabamians,under James J. Archer. After a long fight with Buford's dismounted cavalrymen..Archer's people were soon surprised to see ..'these black hated fellows'...the Federal Iron Brigade!
Soon Archer's men were pushed back and a goodly number of the men were captured..including ' Sally ' Archer.
I do not know of a "First Volley" I'm sure it was ragged at best..as Archer's four regiment in line were seperated with the 7th and 14th Tennessee on the left and the 1st Tennessee Provisional and the 13th Alabama on the right.
(The 5th Alabama Battalion had been skirmishers.)
Now it was a wooded area and the smoke was thick..but as close as they were to each other...little doubt some of the Iron Brigade fell to Archer's rifles..before the roof caved in!
Then however came the brigade of North Carolinians in Heth's division,under Johnston Pettigrew. They shredded the Iron Brigade,while being shredded themselves. The Tar Heels I believe would have been going slightly uphill in their attack and that must have helped the Yanks.
Heth's other two brigades under Davis and Brockenbrough were engaged elsewhere.
There are a couple books I know out about the first day..one by Pfanz and one by Martin.
VS..etc.