That song by Chris Pace was posted by Seamus Kennedy - I just put in the line breaks. It's intended to be sung with the tune of that song about the Alamo and Travis and all -I think they had it in the movie, but I've never seen the movie.

As I've read the story, the hangings were said to have been arranged so they could see the defeat of their comrades and the storming of the fortress as they waited to die, as a way of telling them what they had done had been in vain. If they'd been cheering I'd have doubted they'd be cheering the American troops.

Of course there were a lot of Irish on the American side too, so they could have been - but I can't imagine doing that in the circumstances. Your loyalty would surely be to the people who had fought beside you, the Mexicans defending the fortress against the foreign invader.