This LOC.gov songsheet shows us how Union partisans re-purposed Emmett’s 1859 minstrel walkaround:

The opening lines establish reasons for enlisting in the Union war effort:

Come, Patriots all who hate oppression,
Help us to put down Secession…
Come, Boys, from ev’ry State and station,
Shoulder arms to save the Nation…

The taunting chorus just begs to be shouted out over the battlements at Confederate foes:

Each Dixie-Boy must understand
That he must mind his uncle Sam…

Likewise the following verses:

Away down South in the land of traitors,
Rattle-snakes and Alligators…
Where cotton’s king, and men are chatles,
Union-Boys will win the battles…

As for the general popularity of Dixie & select variants at the North, Hans Nathan quotes an exuberant clipping (c.1861) found in R. G. Shaw’s scrapbook in the Harvard Theatre Collection:

“Dixie” has become an institution, an irrepressible institution in this section of the country … As a consequence, whenever “Dixie” is produced, the pen drops from the fingers of the plodding clerk, spectacles from the nose and the paper from the hands of the merchant, the needle from the nimble digits of the maid or matron, and all hands go hobbling, bobbling in time with the magical music of “Dixie.”  Won’t somebody localize “Dixie,” give it a habitation, a place where it may be hailed from?  Set words of Union sentiment to its “ta la, ta la” and “rum di di di do” etc.

And someone did just that.  Wikipedia lists several other variants (Northern and Southern) of Dixie under its heading, “Lyrics.”