The Fall 2008 issue of the American Jewish Historical Society's Heritage magazine has some great stories. Here's one:

More problematic was the situation of Union soldiers who, unable to hold their own Seders, were forced to "fraternize" with local Southern Jews. Myer Levy of Philadelphia, for example, was in a Virginia town one Passover late in the war when he saw a young boy sitting on his front steps eating a piece of matzo.... When Levy asked the boy for a piece, the child fled indoors, shouting at the top of his lungs, "Mother, there's a damn Yankee Jew outside." The boy's mother invited Levy to Seder that night.