Gibb-

What you say all makes sense. What you haven't explained very satisfactorily is how the winning generals got shifted around in this shanty, from General Taylor to loser General Santa Anna.

I still like the theory (as reprised by Hugill) that the shanty was the product of British sailors who "volunteered" (ex-Royal Navy men) for the Mexican army; they may not have won any battles but their version of the shanty "gained the day" as a shanty.

Cheerily,
Charley Noble