WD 171 was taken on October 9, 1864 which was the date of Tom's Brook. See the colonel of the 2nd Mass Cav who took over Lowell's Brigade when he was killed - and claimed the flag for his regiment instead of the 2nd US Cav. He states the flag was taken during the Confederate fall back.
The 32nd VA Cav Btn is off my radar screen as they had morphed into another regiment by this time which I have detailed in an earlier post and were not part of either CS cavalry division.
Greg Biggs