Chris and John, thanks for the help on this one. Actually Willie and his family had also been in Tasmania, at some period. His father, John Mitchell, escaped from Tasmania, and may have made his way directly to the U.S. from there. There was also a similar episode in the case of the Union general, Thomas Francis Meagher, who had also been a convict in Tasmania, before escaping. I have now come upon an old pamplet written by Mr. Barry Crompton, in 1995, relating to Australian connections in the Civil War, and Willie Mitchell is given a somewhat extensive coverage, as is his father John, and brother, John C.