The VermontCivilWar.Org Database has more than 36,00 names listed, including those who served in Vermont, U.S. and other States' units, and those from other States' units who are buried in Vermont.
REMEMBER: there may be spelling variations from the 1860s to today, so don't give up if the name isn't spelled exactly as you think it should be. Try phonetic spellings variations, English-French conversions, and there is the occasional person who enlisted under an assumed name.
Maybe he did not enlist under his own name. We have put together a small list of aliases, based on descendant's input and pension record index cards. It is probably woefully inadequate, but at least it is a start.
ALSO, names with apostrophe (') will not work unless you use a two apostrophes. Thus, to find O'Neil, search for o''neil, etc..
Formatting your search: enter your name using Surname, or Surname, Given Name.
For example, Smith or Smith, John.
This retrieval will return a maximum of 50 responses, so give as much of the name as possible.