A personal note. (I have posted this information before.) My great-grandfather (sic my father's maternal grandfather) emigrated from Dublin and fought with the New York Infantry at First Manassas. He was discharged when his 90 day enlistment was over. He must have reenlisted because he was listed as deserting on the March to Chancellorsville on May 2, 1862. I do not know where he wound up, but my great-great-grandfather (paternal all the way) was a police captain fighting Irish rioters at the time of Gettysburg.
Those riots remind us that the wars our country has fought were not as popular and glorious as they have been portrayed.
In World War I and II the opponents were cracked down on by Wilson and Roosevelt.