Well, those are the facts. As told by Jimmy himself. Glen just sang and performed the song - at an astounding level. Not sure what your post adds to that.
You wrote that the song is about a Galvestonian fighting in the Spanish-American War. When he returns to Galveston after the war concludes, he and his lady love had better make plans to clear out. If they're still in Galveston 25 months after the war ended, they will be very, very, very sorry.