This tune commemorates the Battle of Aughrim, which was the bloodiest battle in the history of Ireland. Traditionally, it's played as a solemn tune.
These are the audio files for Battle of Aughrim - Version 1
These are the audio files for Battle of Aughrim - Version 2
These are the audio files for Battle of Aughrim - chords
Here are some hints for managing the chords:
1) When you are playing rhythm, it is more important to keep the tempo accurate than it is for you to get the notes right. If you are struggling with the chord changes, start by playing only one note in the chord (usually the highest one). When you can play that in time, add a second one. And when you can play those in time, add the third note.
2) Measures 12 and 16 have what is referred to as a "fast" chord change. You've been playing the chord only on the first beat for the whole song, and all of a sudden these two measures have a second chord that you have to play on the third beat. It is more important to get the chord on the first beat of those measures, as well as the one on the first beat of the measures that follow them. So if you're struggling with them, leave those "fast" chords out to start. You can always add them back in when you get more comfortable with the rest of the chords in the song.