Thanks for the responses. I agree with the points both of you make. I have been shown a number of 300,000 which I seriously doubt --No, 300,000 slave owners did not fight on the Union side in the Civil War at http://www.politifact.com/punditfact/statements/2015/jul/27/chuck-baldwin/no-300000-slave-owners-did-not-fight-union-side-ci/
This article seems more intent to prove Baldwin wrong than derive at the number of slave-owners serving the Union army. I did check the source of Townsend, he mentions nothing of slave-owners at all, at least that I can determine. Other than that one fact of relating to 300,000 I see no use of the book.
Like the two of you I see exhausting and time consuming work involved in trying to get any sort of accurate number for such men who served.
1. Rosters would have to be compiled
2. Census records would have to be checked. As Dennis pointed out name of state of unit formation would not automatically disqualify a potential candidate.
3. Slave schedules would have to be crossed referenced to determine ownership.
There maybe be more records I am not aware of that maybe could and should be accessed. Not sure this would be beneficial in any way.
Just my thoughts.