Hi David,
I guess it all depends on how much you "breakup" the engagement. If you divide Gettysburg into six (6) parts, not including the cavalry action at Hanover, as follows:
July 1st
1) The morning of July 1st (McPherson's Ridge)
2) The afternoon of July 1st (Ewell Arrives)
July 2nd
3) Longstreet's Attack on the right (Little Round Top, Peach Orchard, Wheatfield, etc.)
4) Ewells' Attack on Culp's and Cemetery Hill
July 3rd
5) Ewell's Attack on Culp's Hill
6) Pickett's/Pettigrew's Charge
The only one of these I'm concerned about as far as not including Alabamians is #4, Ewell's Attack on Culp's and Cemetery Hill. Though Rodes division, which included O'Neal's brigade, was ordered to participate in this assault on Cemetery Hill, they were not in position until after dark when the fighting was ended.
If you divide the battle into actions on the left, center and right from the Confederate viewpoint then I believe you can absolutely say that Alabama infantry units participated in all three.
Jim
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