Charles,
Archibald is mentioned by name in the source as
being buried with the flag of the regiment.
I have been through the service records of the 15th and
found no mention of a flag being issued at all.
The only two surviving (as far as we know) flags of the 15th
are in the State Museum; The first battleflag and the company
flag of the "Browder Roughs", Company D.
We also know that flags were presented to the following
companies; A, C, F, G, & I, none of which can now be located,
if indeed they survived.
May I ask what prompted the interest?

Ken