It is worth noting that the Irish Brigade was a Union unit consisting of 3 Regiments from New York (63rd New York Infantry, 69th New York Infantry & 88th New York Infantry) and others from Massachusetts and Pennsylvania. However, this Brigade was predominantly Catholic and was partly set up to ensure that Irish Americans (who supported Irish Independence) would not see the Confederacy as their “natural” revolutionary friends. [Ref: Wikipedia: Irish Brigade (Union army) - note that this article is not very well referenced]
American Civil War Records may give a route into finding WB Williamson’s parents.
However, if Civil War records (for either side) show a youngish (George) Thomas (b New Jersey) and George Henry Williamson (b London) in the same unit, we may have found them. Unfortunately the indexing of these records does not make such a check easy!
