Love the Wolfe Tones, but I think their best fuck-the-Black-and-Tans song is “The Rifles of the IRA.”
In the spirit of peace and good will, though, I’ll choose the grand auld trad song “The Bold Thady Quill.”
That’s my preferred version, but the Clancy Bros version is better enunciated and much easier to understand:
Traditional:
*Oh, have you forgotten how soon we must sever?
Oh, have you forgotten this day we must part?
It may be for years and it may be forever,
Oh, why are you silent, thou voice of my heart?
It may be for years and it may be forever,
Then why are you silent, Kathleen Mavourneen? *
The one that makes me smile every time I hear it:
Should also do a call-out to Dervish, still the most amazing Irish trad jam band out there.
Cathy Jordan must have about half faerie blood in her veins. Best voice in the Connaught.
Anything Ronnie Drew sings, especially Champion at Keeping Them Rolling. Have a listen.
This entire album by The Clancy Brothers & Tommy Makem.
The Crying Song. There may be more than one.
I’m not sure if this qualifies. Ireland? They’d know better than I would.
They were only fookin’ born there. Who am I to say?
The Foggy Dew, by Sinead O’Connor and The Chieftains.
Beaten to it.
I absolutely love “Ar Éireann Ní Neosainn Cé Hí”. The High Kings do a great job here: https://www.youtube.com/watch?v=dcNc_zUanSU.
Such a hauntingly beautiful song.
Or the cover of “Fields of Athenrye” by Seanchai & The Unity Squad (aka Chris Byrne formerly of B47) Not the best recording as it is from a live show vs. studio mix but still… “F-CK THE CROWN!” 
If I Should Fall from Grace with God - The Pogues
There are many songs by The Pogues you could have on this list. I just chose this one because it was the first one that came to mind.
Happy St.Paddy’s Day.
Glory O, Glory O, to our Bold Fenian Men
Black Velvet Band…I’ve heard it by a couple of different bands, but I’ve enjoyed it each time.
Psst… see the description.
Mine is this too, as I appreciate insults when they’re done sarcastically, and “show your wives how you won medals down in Flanders” is delicious shade-throwing.
It’s by Dominic Behan, Brendan’s brother. Also known for “the Patriot Game.”
Oh Danny Boy !
Arthur McBride, by Planxty - YouTube
The definitive Danny Boy, by the Leprechaun Brothers. Link