Jim...

I believe he is referring to Cold Harbor (Second Cold Harbor in 1864) and not the 1862 Battle of Gaine's Mill. I could not find the 48th AL in the order of battle for Gaine's Mill. They do show up in Law's Brigade (along with the 15 Al, 44AL, 47AL) for Cold Harbor; Gregg's Brigade included 3Ark, 1 TX, 4 TX, and 5 TX. Also, I don't believe there were any black troops present at Gaine's Mill (plenty of New Yorkers).

John