Look here! From http://en.wikipedia.org/wiki/Alasdair_Mac_Colla (I have not checked the accuracy of this entry.)

Gol na mBan san Ár (English: Lament of the Women in the Massacre) was composed in memory of MacColla and his female followers. The song has been recorded under many names.

    * 1980 - The Chieftains - Boil the Breakfast Early
    * 1993 - Noel Hill, Tony MacMahon & Iarla Ó Lionáird - Aislingí Ceoil (Music Of Dreams)
    * 2008 - Julie Fowlis & Muireann Nic Amhlaoibh - Dual
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There is a link on that entry leading to:
http://www.thesession.org/tunes/display/4192

Gol Na MBan San Ar
waltz

Key signature: Dmajor

Submitted on February 2nd 2005 by fidkid.

This tune has been added to 50 tunebooks.

Also known as Arrane Ny Niee, The Crying Of The Women At The Slaughter, Eagle's Whistle, The Eagle's Whistle March, The Eagle's Whistle, Eagles Whistle, The O'Donovan Clan March.

Recordings of a tune by this name:

    * 40th Anniversary Album by Armagh Pipers Club
    * Boil The Breakfast Early by The Chieftains
    * Celtic Celebration by Dirk Freymuth
    * Dual by Dual
    * Far From Home by Boys Of The Lough
    * Jiggin' The Blues by Frankie Gavin, Rick Epping And Tim Edey
    * Little Woolly, Lullabyes by Kelly Hood
    * Live by Blazin' Fiddles
    * Magnificent Seven by Blazin' Fiddles
    * Music Of Dreams by Noel Hill And Tony MacMahon With Iarla O Lionaird
    * Open Road by Boys Of The Lough
    * Paddy On The Railway by Ten Penny Bit
    * Pipes, Rods 'n' Reels by Ray Sloan
    * Shatter The Calm by Dan Beimborn
    * The Best Of Joe And Antoinette Mckenna by Joe And Antoinette McKenna
    * The Eagle's Whistle by Michael Tubridy
    * The First Measure by Pipedown
    * The Little Country by Charles De Lint
    * The Music Makers: Celebrating 35 Years Of Comhaltas In Leeds by Leeds CCE
    * Traditional Music Of Ireland by Joe And Antoinette McKenna
    * Uilleann Pipes by Pat Mitchell
    * We'll Seek No More Engagements by Aidan Crossey
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So we may have found the composer; we have no good source for any of the sets of lyrics yet.