The answer to the first question is Nelson G Williams.
The answer to the bonus question is a.) Calixa Lavallee. B.) he wrote the national anthem for Canada. C.) the tune is called O Canada. I was reading further up on him and it looks like he played the cornet for the 4th Rhode Island and was wounded at Antietam.
Edit - Both of your responses are correct, Michigander. 20 points for you.
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The composer was Calixa Lavallée (December 28, 1842 – January 21, 1891). In 1880 he composed "O Canada" to a patriotic poem by Adolphe-Basile Routhier, commissioned by the Lieutenant Governor of Québec, Théodore Robitaille. "O Canada" had served as a de facto national anthem since 1939 and officially become the country's national anthem in 1980 when Canada's National Anthem Act received royal assent.